Solve for missing value: A : B = C : ?
About Ratio Calculator
Solve ratio and proportion problems by finding missing values, simplifying ratios, and scaling values up or down. Enter any three of four values in a proportion and the tool solves for the missing one. Useful for cooking, maps, models, finance, and everyday proportional reasoning.
How to Use Ratio Calculator
- 1
Enter your known values
Input the known numbers in the ratio or proportion fields.
- 2
Identify the unknown
Leave the missing value blank.
- 3
Solve
Click Solve to calculate the missing value and see the simplified ratio.
Common Use Cases
- Scaling recipe ingredients up or down for different serving sizes
- Calculating map distances using a scale ratio
- Solving proportion problems in math and science homework
- Determining scale factor for model building or architectural drawings
Frequently Asked Questions
How do I solve for a missing value in a proportion?
Can I simplify a ratio?
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