Ratio Calculator

Simplify a ratio to lowest terms and scale it up or down.

Ratio Calculator

Worked example result

Simplified ratio	2:3
Simplified a	2.00
Simplified b	3.00
Scaled ratio	16:24
a ÷ b as a decimal	0.6667
Total parts (a + b)	20.00

8:12 simplifies to 2:3 (both sides divided by the GCD, 4). Scaled by 2, the original ratio becomes 16:24 — a different size, but exactly the same proportion.

A ratio compares two quantities, written a:b. Simplifying a ratio works exactly like simplifying a fraction: divide both sides by their greatest common divisor, so 8:12 becomes 2:3.

Enter the two parts and a multiplier to scale the ratio — useful for recipes, screen dimensions, map scales and mixing quantities, where the proportions must stay the same while the amounts change.

The formula

Simplified ratio = (a ÷ GCD) : (b ÷ GCD); Scaled ratio = (a × k) : (b × k)

Worked example

8:12 simplifies to 2:3 (both sides divided by the GCD, 4). Scaled by 2, the original ratio becomes 16:24 — a different size, but exactly the same proportion.

The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.

Frequently asked questions

How is a ratio different from a fraction?

A fraction like 2/3 describes part of one whole. A ratio like 2:3 compares two separate quantities — 2 parts of one thing to 3 parts of another — so the whole is actually 5 parts.

How do I split an amount using a ratio?

Add the parts to get the total, divide the amount by that total, then multiply by each part. Splitting $100 in a 2:3 ratio: $100 ÷ 5 = $20 per part, giving $40 and $60.

Category: Math calculators

Ratio Calculator