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.
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 ratio or solve one missing term in an equivalent proportion, including decimal, zero, and sign validation.
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.
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.
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.
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, legal conclusions, medical advice, supplier guarantees, or code approvals.