Everyday tool
Ratio & Proportion Calculator
Enter three values to solve the fourth value in a:b = c:x.
Runs in your browser. No upload.
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Solve A:B = C:X, then see the simplified A:B ratio.
Missing value X
Simplified A:B
About this tool
Ratio & Proportion Calculator made simple.
Use it for recipes, scale drawings, discounts, mixtures and any proportional relationship.
Common questions
About Ratio & Proportion Calculator.
How do I solve a proportion?
Enter three values in A:B = C:X. The calculator finds the missing value X locally.
Can I use this for recipes and scale drawings?
Yes. Ratios are useful for adjusting recipes, comparing quantities and scaling measurements.