GPA calculations
Calculate course GPA, combine terms, or estimate a target using your own school scale and credit rules.
Academic arithmetic
GPA Calculator
Calculate credit-weighted, unweighted, or weighted GPA with an editable grade scale.
Academic arithmetic
Cumulative GPA Calculator
Combine an existing GPA with a new term or estimate the future GPA needed for a target.
Grade and study planning
Calculate weighted grades, test scores, explicit grade curves, and user-directed study-time allocations.
Education planning
Weighted Grade Calculator
Calculate a course grade from scores and weights using either complete-course weights or normalized entered weights.
Education planning
Test Grade Calculator
Convert questions correct, questions wrong, or earned points into a test percentage with an editable example letter scale.
Education planning
Grade Curve Calculator
Apply one explicitly selected mathematical grade curve to up to 50 entered scores.
Education planning
Study Time Planner
Allocate a user-entered study-time budget proportionally across tasks using editable priority weights.
Recipe and baking calculations
Scale ingredients, compare pans, estimate entered costs, and calculate baker percentages.
Recipe arithmetic
Recipe Scaling Calculator
Scale manually entered ingredient quantities between original and target servings using decimals, fractions, or mixed numbers.
Recipe arithmetic
Baking Pan Converter
Compare round, square, and rectangular baking pans using an explicit equal-depth area ratio or entered-depth volume ratio.
Recipe arithmetic
Recipe Cost Calculator
Calculate ingredient cost, total recipe cost, and optional cost per serving from package prices entered by the user.
Recipe arithmetic
Baker's Percentage Calculator
Calculate baker's percentages, dough weight, formula percentage, and water-based hydration from ingredient weights.
Everyday commerce calculations
Calculate tips, discounts, margin, and markup from values you supply without pricing, accounting, tax, or tipping recommendations.
Everyday commerce
Tip calculator
Calculate a tip, total bill, and equal per-person split from a custom percentage.
Everyday commerce
Discount calculator
Calculate percent off, savings, and final sale price or reverse-calculate the discount.
Everyday commerce
Margin calculator
Calculate profit margin or solve a selling price for a target margin.
Everyday commerce
Markup calculator
Calculate cost-based markup or solve a selling price for a target markup.
Advertising metrics
CPC Calculator
Calculate cost per click, total advertising cost, or theoretical click count with local campaign arithmetic.
Advertising metrics
CPA Calculator
Calculate cost per acquisition, total attributed cost, or theoretical acquisition count.
Advertising metrics
CTR Calculator
Calculate click-through rate, clicks, or impressions from two known advertising counts.
Advertising metrics
ROAS Calculator
Calculate return on ad spend, attributed revenue, or advertising cost using user-entered values.
Loan payments and compound growth
Estimate fixed-rate payments or project compound growth from values and assumptions you supply.
Home financing estimate
Mortgage Calculator
Estimate principal and interest, optional monthly housing costs, and yearly amortization.
Fixed-rate borrowing
Loan Calculator
Calculate payment, interest, total paid, and yearly amortization for an installment loan.
Growth projection
Compound Interest Calculator
Project principal and end-of-period contributions under a stated compounding model.
Vehicle financing
Auto Loan Calculator
Estimate payment, trade equity, sales tax, interest, and yearly amortization from values you enter.
Interest arithmetic
Simple Interest Calculator
Calculate non-compounding interest and ending amount from principal, annual rate, and time.
Payoff estimate
Debt Payoff Calculator
Estimate payoff time, interest, total paid, and yearly balances for one fixed-rate debt.
Detailed loan schedule
Amortization Calculator
Calculate a fixed payment and inspect monthly and yearly principal-interest schedules.
Workplace retirement
401(k) Calculator
Project contributions, optional employer matching, hypothetical growth, and yearly balances.
Extra principal
Mortgage Payoff Calculator
Compare baseline and accelerated mortgage schedules and estimate time and interest saved.
Effective annual yield
APY Calculator
Convert between a nominal annual rate and APY for common compounding frequencies.
Planning & pay
Retirement Calculator
Estimate retirement savings from current savings, monthly contributions, time, and an effective annual return assumption.
Planning & pay
Salary Calculator
Convert gross pay among hourly, weekly, biweekly, semi-monthly, monthly, and annual periods with editable work assumptions.
Planning & pay
Sales Tax Calculator
Add a user-entered sales tax rate to a price or work backward from a tax-inclusive total using browser-local arithmetic.
Planning & pay
Overtime Calculator
Calculate gross regular and overtime pay from an hourly rate, user-classified hours, and an editable overtime multiplier.
Finance
Mortgage Recast Calculator
Estimate a new mortgage principal-and-interest payment after a lump-sum principal reduction with the same rate and remaining term.
Finance
Business Loan Calculator
Estimate fixed business-loan payments, origination fees, net proceeds, interest, and modeled borrowing cost.
Finance
Car Depreciation Calculator
Estimate vehicle value by year with editable declining-balance or straight-line depreciation assumptions.
Finance
Stock Average Calculator
Calculate weighted average stock cost per share across multiple purchase lots, including optional transaction fees.
Finance & business
Debt Snowball Calculator
Simulate a smallest-balance-first debt snowball with payment rollover, payoff order, timing, interest, and a fixed monthly budget.
Finance & business
NPV Calculator
Calculate net present value for periodic cash flows at an entered per-period discount rate with a present-value breakdown.
Finance & business
IRR Calculator
Find supported periodic IRR roots for entered cash flows with deterministic bounded search and multiple-root reporting.
Finance & business
Commission Calculator
Calculate gross sales commission and total gross compensation, or reverse-solve sales required for a target commission.
Finance
Present Value Calculator
Calculate the present or future value of one lump sum with an entered rate, term, and compounding frequency.
Finance
Stock Profit Calculator
Calculate modeled stock profit or loss, percentage return, and break-even price from user-entered shares, prices, and fees.
Finance
Mortgage Points Calculator
Compare entered mortgage rates with and without discount points, including points cost, P&I payments, and simple break-even.
Fractions, factors, and number notation
Use exact rational, integer, Roman-numeral, and scientific-notation tools without creating one page for every possible input value.
Exact math & notation
Decimal to fraction calculator
Convert exact terminating decimals to simplified fractions and mixed numbers.
Exact math & notation
Fraction to decimal calculator
Convert fractions and mixed numbers to terminating or repeating decimals.
Exact math & notation
Roman numeral converter
Convert conventional Roman numerals and integers in both directions.
Exact math & notation
GCF calculator
Find the GCF, GCD, or HCF of two or more integers with exact arithmetic.
Exact math & notation
Scientific notation calculator
Convert, add, subtract, multiply, and divide scientific-notation values.
General scientific math
Scientific Calculator
Evaluate expressions with powers, roots, logs, trigonometry, and degree or radian modes.
Date and time calculations
Add calendar units, measure one clock interval, compare complete date-time values, or count customizable working days without hidden timezone or holiday assumptions.
Date & time
Date Calculator
Add or subtract days, weeks, months, and years from a calendar date with explicit month-end clamping and no timezone drift.
Date & time
Hours Calculator
Calculate hours and minutes between two clock times, including overnight intervals and an optional break deduction.
Date & time
Time Duration Calculator
Calculate elapsed days, hours, minutes, and seconds between two complete civil date-and-time values without hidden timezone conversion.
Date & time
Business Days Calculator
Count business days between dates or add and subtract working days with customizable weekdays and excluded dates.
Browser timer
Stopwatch
Use a precise browser-local online stopwatch with pause, resume, lap times, and reset controls.
Browser timer
Countdown Timer
Set a browser-local countdown timer in hours, minutes, and seconds with pause, resume, quick-add, and optional sound.
Browser timer
Pomodoro Timer
Use a configurable browser-local Pomodoro timer with focus, short-break, and long-break phases.
Browser timer
Interval Timer
Run a browser-local interval timer with preparation, work, rest, rounds, and a Tabata-style preset.
Grades, dates, math, data, and science
Use these focused utilities for weighted grades, integer and algebra work, date intervals, statistics, charts, chemistry, percentages, division, and ratios.
Math foundation
Square Root Calculator
Calculate principal real square roots with exact perfect-square and simplified-radical output.
Math foundation
Fraction Simplifier
Reduce signed integer fractions to lowest terms with exact BigInt arithmetic.
Math foundation
Exponent Calculator
Calculate exact supported integer powers and approximate real powers with explicit domain boundaries.
Math foundation
Factorial Calculator
Calculate exact factorials for nonnegative integers through 5,000.
Physics and coordinate math
Speed Calculator
Solve for speed, distance, or time with explicit physical units.
Physics and coordinate math
Density Calculator
Solve for density, mass, or volume with correct cubic conversions.
Physics and coordinate math
Midpoint Calculator
Find the midpoint between two 2D or 3D coordinate points.
Physics and coordinate math
Distance Formula Calculator
Find Euclidean distance between two 2D or 3D coordinate points.
Measurement and geometry
Square Footage Calculator
Calculate square feet across one or more rectangular sections with explicit mixed units.
Measurement and geometry
Volume Calculator
Calculate volume for five common three-dimensional shapes with correct cubic conversions.
Measurement and geometry
Area Calculator
Calculate general geometric area for six common shapes with squared-unit conversions.
Measurement and geometry
Circumference Calculator
Calculate circle circumference from radius or diameter.
Percentage calculator
Percentage Calculator
Solve the three fundamental percentage relationships for a part, rate, or whole.
Percentage calculator
Percentage Difference Calculator
Compare two values symmetrically using their average absolute magnitude.
Percentage calculator
Percentage Increase Calculator
Measure an increase or increase a number by a selected percentage.
Percentage calculator
Percentage Change Calculator
Calculate signed directional change from an original value to a new value.
Focused math utility
Proportion Calculator
Solve exactly one missing value in a proportion with cross-multiplication steps and undefined-case validation.
Focused math utility
Slope Calculator
Calculate slope from two points and identify vertical, horizontal, and identical-point cases.
Focused math utility
Aspect Ratio Calculator
Simplify a width-to-height ratio and calculate a matching new dimension.
Focused math utility
Weighted Average Calculator
Calculate a weighted average from values and nonnegative numeric or percentage weights.
School & grades
Final grade calculator
Calculate the final exam score needed for a target course grade or the resulting course grade from a known exam score.
Math & geometry
LCM calculator
Find the least common multiple of two or more integers with prime-factor steps, validation, and zero handling.
Math & geometry
System of equations calculator
Solve a two-variable linear system, identify unique, no, or infinite solutions, and review elimination and determinant steps.
Statistics & data
Pie chart maker
Create an accessible local SVG pie chart from category labels and values, with percentages, a legend, and a text table.
Time & dates
Days between dates calculator
Calculate elapsed days and weeks between two calendar dates with optional inclusive counting and leap-year handling.
Math & geometry
Percentage decrease calculator
Calculate absolute and percentage decrease from an original and new value, with clear increase and zero-original handling.
Math & geometry
Long division calculator
Divide integers with quotient, remainder, decimal result, and accessible digit-by-digit long-division working steps.
Statistics & data
Mean calculator
Calculate arithmetic mean, sum, count, median, mode, and range from a numeric dataset with clear steps.
Science
Molarity calculator
Calculate molarity, moles of solute, or solution volume using M = moles per liter with liter and milliliter conversion.
Math & geometry
Ratio calculator
Simplify a two-part ratio with decimal, zero, and sign validation and a clear common-factor step.
Running and walking
Pace Calculator
Calculate pace, time, or distance with mile and kilometer results and race-distance presets.
Work, time, statistics, and math
Use these tools for time cards, clock conversion, advertising ratios, strength estimates, statistics, algebra, dates, and geometry.
Work, time & math
Time card calculator
Add daily clock-in and clock-out times, subtract unpaid breaks, and calculate weekly regular, overtime, and decimal work hours.
Work, time & math
CPM calculator
Calculate advertising CPM, total cost, or impressions by entering any two known values, with formula steps and input validation.
Work, time & math
Military time converter
Convert 12-hour time to military time or 24-hour time back to AM/PM, including midnight, noon, leading zeros, and a complete chart.
Work, time & math
One rep max calculator
Estimate one-repetition maximum from weight and repetitions using Brzycki and Epley formulas, with a visible range and clear limitations.
Work, time & math
Right triangle calculator
Solve a right triangle from two valid known values and calculate missing sides, acute angles, area, perimeter, and hypotenuse.
Work, time & math
Standard deviation calculator
Calculate sample or population standard deviation, variance, mean, count, and calculation steps from an entered numeric dataset.
Work, time & math
Pythagorean theorem calculator
Find a missing right-triangle side from any two known sides using a² + b² = c², with validation and substitution steps.
Math & geometry
Factoring Calculator
Factor supported polynomial expressions with integer-safe parsing, step-by-step methods, and verification by expansion.
Work, time & math
Quadratic formula calculator
Solve ax² + bx + c = 0 with the quadratic formula, discriminant, real or complex roots, validation, and substitution steps.
Work, time & math
Chronological age calculator
Calculate exact chronological age in calendar years, months, and days between a birth date and comparison or test date.
Work, time & math
Cylinder volume calculator
Calculate cylinder volume from radius or diameter and height, with selectable units and cubic-unit, liter, and gallon conversions.
Body metrics
BMI Calculator
Calculate adult body mass index from height and weight in metric or imperial units with a neutral screening-category explanation.
Body metrics
TDEE Calculator
Estimate total daily energy expenditure from Mifflin-St Jeor BMR and a selected conventional activity factor.
Body metrics
BMR Calculator
Estimate adult basal metabolic rate with the Mifflin-St Jeor equation using metric or imperial measurements.
Body metrics
Body Fat Calculator
Estimate adult body-fat percentage from circumference measurements using the U.S. Navy method in inches or centimeters.
Financial and trip planning
Mortgage Refinance Calculator
Compare current and proposed fixed-rate mortgages, closing-cost treatment, payments, interest, lifetime cost, and simple upfront-cost break-even.
Financial and trip planning
Home Affordability Calculator
Estimate a maximum housing payment, mortgage amount, and home price using editable income, debt, housing-cost, rate, and ratio assumptions.
Financial and trip planning
Credit Card Payoff Calculator
Estimate credit-card payoff time and interest from a fixed payment, or calculate the payment needed for a selected target period.
Financial and trip planning
Fuel Cost Calculator
Estimate trip fuel use and cost from distance, fuel economy, price, one-way or round-trip travel, and common US or metric units.
Business, budget, and measurement
ROI Calculator
Calculate return on investment, net profit or loss, total invested cost, and return multiple from values you enter.
Business, budget, and measurement
Rent Calculator
Estimate a monthly rent budget from gross income, an editable rent percentage, debts, essential expenses, and desired savings.
Business, budget, and measurement
CAGR Calculator
Calculate compound annual growth rate, total percentage change, and growth multiple from beginning value, ending value, and elapsed years.
Business, budget, and measurement
Gas Mileage Calculator
Calculate measured fuel economy from distance traveled and fuel consumed as MPG using US gallons, km/L, and L/100 km.
Income and yield
CD Calculator
Estimate certificate-of-deposit maturity value and interest from one opening deposit using APY or a nominal rate and compounding frequency.
Income and yield
Pay Raise Calculator
Calculate before-and-after gross pay from a percentage raise or fixed increase across hourly, weekly, biweekly, semi-monthly, monthly, and annual pay.
Income and yield
Dividend Calculator
Calculate dividend income per payment and year, annual dividend per share, entered-price share value, and dividend yield.
Income and yield
Credit Card Interest Calculator
Estimate one billing cycle of credit-card interest from average daily balance, APR, and cycle length using a stated 365-day convention.
Personal finance
Budget Calculator
Calculate monthly income, expenses, savings, and remaining cash flow with a clear category breakdown.
Personal finance
Net Worth Calculator
Calculate net worth from user-entered assets and liabilities with separate category totals.
Personal finance
Property Tax Calculator
Estimate annual and monthly property tax from entered assessed value, assessment ratio, exemption, and percent or mill rate.
Personal finance
Car Lease Calculator
Estimate a vehicle lease payment from negotiated price, residual value, term, money factor, fees, reductions, and entered tax.
Finance and real estate
Annuity Calculator
Calculate present value, future value, or periodic payment for an ordinary annuity or annuity due.
Finance and real estate
Debt-to-Income Ratio Calculator
Calculate front-end housing and total debt-to-income ratios from entered gross monthly income and recurring debts.
Finance and real estate
Car Affordability Calculator
Estimate a maximum vehicle price from a selected monthly payment, APR, term, down payment, trade equity, fees, and tax.
Finance and real estate
Cap Rate Calculator
Calculate capitalization rate, reverse-solve property value, or calculate annual net operating income.
Construction and material planning
Use a specialized calculator when material density, pool shape, stair geometry, or a particular project volume matters.
Construction & material
Asphalt calculator
Estimate asphalt area, volume, cubic yards, and tonnage from project dimensions, thickness, density, and waste allowance.
Construction & material
Cubic yard calculator
Calculate cubic yards from length, width, and depth using mixed imperial or metric units, with cubic feet, cubic meters, and waste-adjusted results.
Construction & material
Cubic feet calculator
Calculate cubic feet from mixed-unit length, width, and height or depth, with cubic-yard and cubic-meter conversions.
Construction & material
Gravel calculator
Estimate gravel volume and optional tonnage from dimensions or area, depth, waste, supplier density, and user-entered price.
Construction & material
Topsoil calculator
Estimate topsoil cubic feet, cubic yards, and cubic meters from area and depth, with optional settling allowance and user-entered bag volume.
Construction & material
Stone calculator
Estimate stone or rock volume and optional tonnage from area, depth, allowance, and an editable supplier bulk density.
Construction & material
Concrete slab calculator
Estimate concrete slab volume in cubic feet, cubic yards, and cubic meters from length, width, thickness, and optional waste allowance.
Construction & material
Stair calculator
Estimate basic stair geometry from total rise, planning riser target, tread depth, and available run, without claiming code compliance.
Construction & material
Pool volume calculator
Estimate rectangular, circular, or oval pool volume in US gallons, liters, cubic feet, and cubic meters using average depth.
Construction & material
Landscape material calculator
Plan gravel, topsoil, stone, or mulch volume from area and depth, with optional supplier density, waste, and user-entered unit pricing.
Construction & material
Board Foot Calculator
Calculate board feet from lumber thickness, width, length, and quantity, with optional entered price per board foot.
Construction & material
Roofing Calculator
Estimate simple gable-roof area and roofing squares from length, span, pitch, and an editable allowance.
Construction & material
Tile Calculator
Estimate tile quantity and boxes from surface dimensions, tile dimensions, an editable allowance, and tiles per box.
Construction & material
Paint Calculator
Estimate paint gallons and liters from room dimensions, openings, ceiling choice, coats, and entered coverage.
Construction & material
Drywall Calculator
Estimate drywall area and whole sheets from room or direct-area measurements, openings, ceiling choice, sheet size, and allowance.
Construction & material
Concrete Block Calculator
Estimate concrete masonry block count from wall area, openings, effective block-face dimensions, quantity, and allowance.
Construction & material
Wallpaper Calculator
Estimate wallpaper rolls from room wall area, openings, roll dimensions, and an editable allowance.
Home improvement
Flooring Calculator
Estimate flooring area, waste-adjusted purchase area, whole packages, coverage, and optional material cost for multiple rooms.
Home improvement
Sod Calculator
Estimate lawn area and sod rolls, pieces, or pallets using supplier coverage for multiple lawn sections.
Home improvement
Baseboard Calculator
Estimate net baseboard linear length and whole stock boards for multiple rooms after subtracting openings.
Construction & material
Fence Calculator
Estimate fence panels and posts from total length, panel width, post spacing, gates, and an editable allowance.
Construction & material
Deck Calculator
Estimate decking board rows, linear footage, whole stock boards, waste, and optional material cost for a rectangular deck.
Construction & material
Siding Calculator
Estimate siding area, squares, and optional package count from multiple walls, openings, gables, and allowance.
Construction & material
Brick Calculator
Estimate brick quantity using wall area, openings, brick dimensions, mortar-joint module, allowance, and optional cost.
Construction & material
Rebar Calculator
Estimate rectangular rebar-grid bar counts and linear footage from user-entered dimensions, spacing, edge cover, and waste.
Statistics and distributions
Standardize values, calculate normal and Student t probabilities, and build common confidence intervals with explicit methods.
Statistics
Z Score Calculator
Calculate a z-score from a raw value, mean, and standard deviation, or solve a raw value from a z-score.
Statistics
Normal Distribution Calculator
Calculate left-tail, right-tail, interval, or outside probabilities for a normal distribution.
Statistics
P Value Calculator
Calculate left-tailed, right-tailed, or two-tailed p-values from a z or t statistic.
Statistics
Confidence Interval Calculator
Calculate z, Student t, or Wilson score confidence intervals with common or custom confidence levels.
Descriptive and inferential statistics
Summarize numeric data, fit a simple regression line, and calculate chi-square results with browser-local methods.
Statistics
Median Calculator
Find the median of a numeric dataset, with sorted values and middle positions.
Statistics
Mean Absolute Deviation Calculator
Calculate mean absolute deviation from the arithmetic mean for a numeric dataset.
Statistics
Linear Regression Calculator
Fit a simple least-squares regression line from paired X and Y values.
Statistics
Chi Square Calculator
Calculate chi-square goodness-of-fit, independence, or statistic-to-p-value results.
Statistics
Percentile Calculator
Calculate any percentile from a numeric dataset with inclusive interpolation, or find a value’s percentile rank.
Statistics
Sample Size Calculator
Estimate a proportion survey sample size from confidence, margin of error, expected proportion, and optional population.
Statistics
T-Test Calculator
Calculate one-sample or independent Welch t-test statistics, degrees of freedom, and local p-values.
Statistics
ANOVA Calculator
Run a one-way independent-groups ANOVA from raw numeric groups with an ANOVA table, p-value, and eta squared.
Statistics
Standard Error Calculator
Calculate standard error for a mean, proportion, successes and trials, or a raw numeric sample.
Statistics
Covariance Calculator
Calculate sample or population covariance from two paired numeric datasets with strict pair preservation.
Statistics
Effect Size Calculator
Calculate Cohen's d and bias-corrected Hedges' g from two independent groups’ summary statistics.
Statistics
Geometric Mean Calculator
Calculate the geometric mean of positive numeric observations with stable log-domain arithmetic.
Advanced math and linear algebra
Work with matrices, logarithms, cross products, and real cube roots using browser-local calculations.
Advanced math
Matrix Calculator
Add, subtract, multiply, scale, transpose, invert, and row-reduce matrices up to 6 by 6.
Advanced math
Log Calculator
Calculate base-10, natural, base-2, or custom-base logarithms and reverse logarithms.
Advanced math
Cross Product Calculator
Calculate a 3D vector cross product, its magnitude, or a 2D scalar z-component.
Advanced math
Cube Root Calculator
Calculate exact integer cube roots or decimal approximations for positive and negative real numbers.
Geometry
Triangle Calculator
Solve a general triangle from SSS, SAS, or ASA/AAS inputs, including all sides, angles, perimeter, and area.
Geometry
Arc Length Calculator
Calculate circular arc length from radius and a central angle entered in degrees or radians.
Geometry
Sector Area Calculator
Calculate the area of a circular sector from radius and a central angle in degrees or radians.
Geometry
Trapezoid Calculator
Calculate trapezoid area and midsegment, entered-leg perimeter, or reverse-solve height and a missing base.
Science
Molecular Weight Calculator
Parse a chemical formula locally and calculate molar mass with per-element counts, atomic weights, and contributions.
Science
Dilution Calculator
Solve stock volume, final concentration, final volume, or required stock concentration with the C1V1 = C2V2 relationship.
Science
Kinetic Energy Calculator
Calculate classical kinetic energy or reverse-solve mass and velocity with common mass, speed, and energy units.
Science
Wavelength Calculator
Solve wavelength, frequency, or propagation speed with v = fλ using common wave units and an editable light-speed preset.
3D geometry
Surface Area Calculator
Calculate total surface area for a cube, rectangular prism, cylinder, sphere, or cone with formula breakdowns.
Classical mechanics
Acceleration Calculator
Calculate average acceleration, final velocity, initial velocity, or elapsed time with explicit motion units.
Classical mechanics
Force Calculator
Solve force, mass, or acceleration with Newton’s second law and explicit SI or imperial unit conversion.
Classical mechanics
Torque Calculator
Calculate general mechanical torque, force, or lever arm from force-vector angle and explicit units.
Classical mechanics
Momentum Calculator
Solve classical linear momentum, mass, or signed velocity with common mass and speed units.
Combinatorics and number tools
Add finite lists, count ordered and unordered selections, and find common denominators with carefully bounded browser-local calculations.
Combinatorics and number tools
Sum Calculator
Add a finite list of numbers accurately, including decimals, negatives, and scientific notation.
Combinatorics and number tools
Combination Calculator
Calculate nCr exactly for unordered selections without repetition.
Combinatorics and number tools
Permutation Calculator
Calculate nPr exactly for ordered arrangements without repetition.
Combinatorics and number tools
Least Common Denominator Calculator
Find the least common denominator of multiple fractions and rewrite equivalent fractions exactly.
Correlation, distributions, and variability
Measure linear association, binomial probabilities, dataset variance, and relative variability with explicit statistical assumptions.
Statistics
Correlation Coefficient Calculator
Calculate Pearson correlation from paired X and Y data with stable browser-local arithmetic.
Statistics
Binomial Distribution Calculator
Calculate exact, cumulative, tail, and interval binomial probabilities with stable local methods.
Statistics
Variance Calculator
Calculate population or sample variance from a numeric dataset using Welford’s stable method.
Statistics
Coefficient of Variation Calculator
Calculate coefficient of variation from a dataset or directly from a positive mean and standard deviation.
Probability and discrete distributions
Calculate general event relationships and discrete probabilities with explicit models and stable local methods.
Probability
Probability Calculator
Calculate single-event, complement, independent AND, union, and conditional probabilities.
Probability
Hypergeometric Distribution Calculator
Calculate exact, cumulative, tail, and range probabilities for sampling without replacement.
Probability
Poisson Distribution Calculator
Calculate exact, cumulative, tail, and range Poisson probabilities from an average event rate.
Probability
Geometric Distribution Calculator
Calculate geometric waiting-time probabilities using either common first-success convention.
Exact number math
Fraction Calculator
Add, subtract, multiply, or divide two fractions with exact reduced results, mixed numbers, and decimal approximations.
Exact number math
Prime Factorization Calculator
Find the exact prime factors of a positive integer up to one trillion with a clear exponent-form result.
Exact number math
Mixed Number Calculator
Add, subtract, multiply, or divide mixed numbers with exact improper-fraction conversion and reduced results.
Exact number math
Prime Number Calculator
Check whether a nonnegative integer up to 2^64 − 1 is prime using a deterministic browser-local test.
Date and time
Decimal Hours Calculator
Convert hours and minutes to decimal hours, or decimal hours back to hours and minutes, using browser-local calculations.
Date and time
Days Until Calculator
Count calendar days from a chosen start date to a future or past target date, with weeks and weekday context.
Date and time
Day of Week Calculator
Find the weekday for a Gregorian calendar date with date-only browser-local arithmetic.
Date and time
Months Between Dates Calculator
Find complete calendar months and remaining days between two dates with a documented month-end rule.
Shared accuracy controls
- Inputs are validated before calculation.
- Formulas and worked examples stay visible.
- Conversions use deterministic factors.
- Displayed rounding does not change the underlying calculation.
Privacy and boundaries
- Calculator inputs remain in the browser.
- Analytics records only safe tool actions after consent.
- Each result states its important assumptions.
- Policy, legal, medical, and professional decisions require separate verification.
These tools provide calculation aids and planning estimates, not bids, engineering specifications, financial advice, legal conclusions, medical advice, supplier guarantees, or code approvals.