Ratio Calculator
Solve, simplify and split ratiosRuns locally · nothing uploaded
A : B = C : D. Leave exactly one box empty to solve it.
:=:
D
20
Also works as:proportion calculatorsimplify ratioaspect ratiodivide in ratio
How it works
When to use it
- Scale recipes, drawings or image sizes.
- Simplify a ratio or split an amount by a ratio.
Formula
A : B = C : D ⇔ A × D = B × CSimplify by dividing every term by the GCDShare = total × part ÷ sum of partsWorked example
Given: 3 : 4 = x : 20; simplify 12 : 18; split 1,000 by 2 : 3
- x = 3 × 20 ÷ 4 = 15.
- GCD(12, 18) = 6 → 2 : 3.
- 1,000 × 2/5 = 400; 1,000 × 3/5 = 600.
Result: x = 15; 2 : 3; 400 and 600.
Reading the result
- Decimal ratios are scaled to whole numbers first: 1.5 : 2 = 3 : 4.
Limitations
- You can't solve for a term when another term is 0.
How to use
- 1Choose a mode: solve, simplify or divide.
- 2Enter the ratio and values.
- 3Results update instantly.
FAQ
How do I solve a proportion?
Cross-multiply: A × D = B × C. For 3:4 = 15:x, x = 4 × 15 ÷ 3 = 20.
How do I simplify a ratio with decimals?
Scale every term to whole numbers, then divide by the GCD. 0.5:1.25 → 50:125 → 2:5.
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