Interactive Ratio calculator
Calculated result
Enter the known values and select Calculate.
How to use this calculator
- Choose simplify ratio or solve a missing proportion value.
- Enter both ratio terms, or enter exactly three of four proportion terms.
- Calculate and review the common-factor or cross-product step.
- Keep compared quantities in compatible units.
Formula and method
Simplification divides both ratio terms by their greatest common divisor after scaling decimals to integers. For a:b = c:d, cross products satisfy a × d = b × c.
Worked example
The ratio 1.5:2.25 scales to 150:225 and simplifies to 2:3. For 2:3 = 8:x, x = 3 × 8 ÷ 2 = 12.
Assumptions and result interpretation
- Finite values with up to six decimal places are supported for simplification.
- A ratio cannot have both terms equal to zero.
- A proportion is rejected when its known denominator relationship would require division by zero.
- Signs are normalized so a negative sign appears on the first simplified term.
Understanding the result
Equivalent ratios preserve the same quotient and cross products. Simplification changes the scale of the terms, not the relationship between them.
Common mistakes
- Comparing unlike units without conversion
- Dividing the two sides by different factors
- Entering all four values in missing-term mode
- Treating 0:0 as a defined ratio
Methodology note
The calculation follows the deterministic formula shown above and runs locally in the browser without a remote calculation service.
This deterministic utility is a calculation aid. Confirm definitions, required precision, and any course, laboratory, professional, or policy requirements separately.