Ratio Calculator
Simplify a ratio, scale it to a total, or find the missing number (x) in a proportion. Every calculation updates live as you type.
1. Simplify a Ratio
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Dividing both numbers by their GCD gives the smallest form.
2. Scale a Ratio
Scaled parts
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3. Solve a Proportion — find x
First case: a : b = c : x
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Second case: a : b = x : d
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How to use
- Simplify: enter the two numbers (a and b) in the first tool — the reduced ratio appears live.
- Scale: enter a ratio a:b plus a target total (or the known first part) in the second tool — the scaled parts show instantly.
- Solve: enter a, b and c in the third tool to find x in a:b = c:x.
- All three tools update live as you type, so just change any number to see new results.
How it works
A ratio shows the relation between two quantities — for example, a recipe with 2 cups of flour and 3 cups of sugar has the ratio 2:3. Simplifying a ratio is just like simplifying a fraction: divide both numbers by their largest common factor.
- Example 1: 12:18 simplifies to 2:3 (both divided by 6).
- Example 2: scaling the ratio 2:3 to a total of 100 gives parts 40 and 60.
- Example 3: in 2:3 = 10:x, x = (3 × 10) ÷ 2 = 15.
Note: the proportion formula is cross-multiplication — if a:b = c:x then x = (b × c) ÷ a.