How do I simplify a ratio?

Divide both parts by their GCF. E.g. 12:8 — GCF(12,8)=4 — 12/4:8/4 = 3:2.

How do I scale a ratio?

If the ratio is 3:2 and A=15, calculate B = 15 × (2/3) = 10. Result: 15:10, which equals 3:2.

What are equivalent ratios?

Equivalent ratios describe the same proportion. 1:2, 2:4, 3:6, 4:8 are all equivalent.

How do I convert a ratio to percentages?

Ratio A:B means A/(A+B) × 100% and B/(A+B) × 100%. E.g. 3:1 → 75% and 25%.

📐 Ratio Calculator

Simplify ratios (12:8 → 3:2), scale a ratio from a known value, view equivalent ratios or convert a ratio to percentages.

A : B

Simplified

3 : 2

÷ 4

The ratio calculator lets you simplify, scale and compare ratios with ease. You can reduce a ratio to its lowest terms, find equivalent ratios and convert a ratio to a percentage in just a few seconds.

How the calculator works and what it’s for▾

How the calculator works

Simplifying a ratio relies on the greatest common divisor: both numbers are divided by the same factor, so the ratio stays the same while the numbers shrink. For example, 12:8 reduces to 3:2.

Scaling, on the other hand, multiplies both parts by the same number, giving you the same ratio with larger or smaller values.

What you can do

You can simplify a ratio, scale it to the size you need, find equivalent ratios, and convert a ratio to a percentage. That way the same information can take whatever form suits your task.

Where ratios are used

Ratios come up in cooking when scaling recipes, in construction for mixing proportions, in maps and drawings for scale, and in finance for splitting amounts.

The percentage conversion helps you see what share each part represents of the whole.

A handy tip

When comparing two ratios, reduce both to the same form so you can instantly tell whether they are equal. Also make sure both parts use the same unit.

🔄 Reviewed June 2026