Ratio Calculator
Calculator ToolsSolve and simplify ratios
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History
All history →Ratio Calculator — at a glance
Reduce any ratio to its simplest form and find the missing number in a proportion.
12 : 18
C = 50
Run
Simplified 2 : 3
D = 75
How to use it — step by step
Two numbers A and B for the ratio, and optionally a third number C to find D.
1
Enter your values
Fill in the boxes. Sensible example values are already filled in for you.
2
Calculate Ratio
Press the button. The answer is worked out instantly on your device.
3
Read or copy the result
See the big answer and the extra details, then press Copy to keep them.
Pro tips
Small things that make the result better.
✦Leave C empty if you only want the simplified ratio.
✦D = B × C ÷ A keeps the same proportion.
✦Use it to scale recipes: if 12 g needs 18 ml, how much for 50 g?
Quick facts
Simplifylowest terms
Proportionsolve for D
Decimalssupported
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Frequently Asked Questions
Can I use decimals?+
Yes. They are converted to a whole-number ratio before simplifying.
What does D mean?+
D is the missing number that keeps the same ratio: A : B = C : D.
Is my data safe?+
Yes. Everything runs inside your own browser. Your text, files and images are never uploaded to any server.
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