Ratio Calculator
Simplify ratios, convert to decimals/percentages, and scale proportionally.
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Quick Tip
Enter the two parts of the ratio, A and B.
About This Tool
Why use Ratio Calculator?
A ratio compares two quantities. This tool simplifies a ratio to its smallest whole-number form by dividing both sides by their greatest common divisor, and shows the same relationship as a decimal, a fraction and a percentage of the total.
It also scales ratios: fix one side to the value you actually have and the other side is worked out for you, which keeps mixes and recipes in proportion. For example 16 : 24 simplifies to 2 : 3, where the first part is 40% of the total; scaling that to 50 on the first side gives 50 : 75.
Key Benefits
Simplifies to whole numbers
Both sides are divided by their greatest common divisor, giving the smallest equivalent ratio.
Ratio, decimal, fraction and percentage
The same relationship in four forms, which makes it easy to drop into a report or a recipe.
Scaling in either direction
Fix side A or side B and the other side follows, so you can size a mix to the amount you have.
How to use Ratio Calculator
- 1
Enter the two parts of the ratio, A and B.
- 2
Read the simplified ratio, its decimal value and A as a percentage of the total.
- 3
To scale, choose which side you know and enter its real value.
- 4
Use the scaled pair for your mix, recipe or split.
Best use cases
Scale a recipe up or down while keeping the proportions right.
Mix concrete, paint, fuel or fertiliser at the specified ratio.
Split a bill, profit or prize between two people.
Convert an aspect ratio into a decimal to check screen or image dimensions.
Ratio Calculator FAQs
How do I simplify a ratio?
Divide both sides by their greatest common divisor. For 18 : 24 the GCD is 6, so the simplified ratio is 3 : 4.
What is the difference between a ratio and a fraction?
A ratio compares two parts to each other (3 : 4), while a fraction compares one part to the whole (3/7 of the total). Both describe the same split.
How do I scale a ratio?
Multiply both sides by the same number. If 2 : 3 must become 50 on the first side, multiply by 25 to get 50 : 75.
Can a ratio have decimals?
Yes, but ratios are normally written with whole numbers. Multiply both sides by 10 or 100 to clear the decimals, then simplify — 1.5 : 2 becomes 15 : 20, which simplifies to 3 : 4.
Related Math Tools
More free math tools that work well alongside ratio calculator.