Ratio Calculator
Simplify ratios, scale them and solve for a missing term.
Enter your values
Results update instantly as you type — no submit needed.
Results
- Missing value D
- 45
- Simplified ratio
- 2 : 3
- As a decimal
- 0.6667
- As a percentage split
- 40% / 60%
Quick answer
Ratios compare quantities; A:B = C:D means A×D = B×C, which lets you solve for any missing term.
A : B = C : D ⟹ A·D = B·C
How to use the Ratio Calculator
- 1Enter the two parts of your ratio.
- 2To solve a proportion, fill in one of C or D and leave the other blank.
- 3Read the simplified ratio and missing term.
Frequently asked questions
How do I scale a recipe ratio?
Multiply both sides by the same factor. 2:3 doubled is 4:6, which is the same ratio in different quantities.
What is a proportion?
A statement that two ratios are equal. Cross-multiplying turns it into a simple equation you can solve.