Ratio Calculator
Three ratio tools in one. Simplify reduces a ratio to its lowest whole-number terms — 1920:1080 becomes exactly 16:9 rather than 1.777:1 — and handles decimals by scaling them up to whole numbers first, so 2.5:5 correctly reduces to 1:2. The proportion solver takes A:B = C:D with any one of the four values left blank and works out the missing one, showing the rearranged formula it used, since each of the four positions needs its own rearrangement and reusing a single formula is where most ratio calculators go wrong. The share tool splits a total between any number of parts and shows each share as an amount, a number of parts and a percentage.
How it works
A ratio can be written as 16:9, 16/9, 16 to 9 or just 16 9, and may have more than two terms. Decimals are fine — they are scaled up to whole numbers before the reduction, so 2.5:5 comes out as 1:2.
Reduce a ratio to its lowest whole-number terms.
Other ways to write it
Frequently asked questions
How do I write a ratio?
Any of 16:9, 16/9, 16 to 9 or 16 9 will be read the same way, and you can use more than two terms — 5:3:2 works.
Can I simplify a ratio with decimals in it?
Yes. Decimal terms are scaled up to whole numbers before the reduction, so 2.5:5 comes out as 1:2 rather than being rejected.
How does the proportion solver work?
Fill in three of the four boxes in A:B = C:D and leave one empty. Cross-multiplying gives A × D = B × C, and the formula rearranged for your particular blank is shown with the answer.
How do I split an amount in a ratio?
Use the share tab: enter the total and the ratio, and each share is given as an amount, its number of parts and its percentage of the whole.
What does the "divided by the smallest term" row mean?
It rewrites the ratio with its smallest term as 1 — so 16:9 becomes 1.7778:1. That is the form usually quoted for aspect ratios and gear ratios.
Can I use this for aspect ratios?
Yes — that is the most common use. Simplify 1920:1080 to see 16:9, or use the proportion solver to find the width that matches a given height at a fixed ratio.
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