Basic Math Guide
Ratio and Proportion Calculator Guide
Simplify ratios and solve simple proportions for recipes, maps, scaling, and comparisons.
Quick answer
A ratio compares two quantities. A proportion says two ratios are equal. If 24:36 simplifies to 2:3, both numbers were divided by 12. If 4:10 = 6:x, then x = 10 x 6 / 4 = 15.
Why this matters
Ratios and proportions are used for recipes, maps, model scaling, classroom math, mixing, design, and comparison. They keep relationships stable while the actual quantities change. If a recipe has a 2:3 ratio, doubling both sides keeps the taste relationship similar.
Example
A drink mix uses 2 parts syrup to 5 parts water. If you use 6 parts syrup, the matching water amount is 15 parts because 2:5 = 6:15. A proportion calculator makes that scaling explicit instead of relying on a guess.
How to use the calculator
Use the ratio calculator to reduce two values. Use the proportion calculator when you know three values and need the fourth. Keep units consistent. Do not compare 2 cups to 300 grams unless you know the conversion and density.
Common mistakes
One mistake is reversing the ratio order. A 2:5 mix is not the same as 5:2. Another is adding the same number to both sides instead of multiplying both sides by the same factor. A third is using proportions when the relationship is not actually linear.
When not to rely on this estimate
For chemical mixtures, medicine, engineering, or safety-sensitive scaling, use official instructions and qualified review. Simple proportions assume a direct linear relationship.
FAQ
What is a ratio?
A comparison between two quantities.
What is a proportion?
An equation showing two ratios are equal.