The two formulas
- Share of total: A ÷ (A + B) × 100. In 1:3, A is 1 ÷ 4 = 25% of the total.
- Compared with B: A ÷ B × 100. In 1:3, A is 1 ÷ 3 = 33.3% of B.
Common ratios as percentages
| Ratio A:B | A as % of total | B as % of total | A as % of B |
|---|---|---|---|
| 1:1 | 50.0% | 50.0% | 100.0% |
| 1:2 | 33.3% | 66.7% | 50.0% |
| 1:3 | 25.0% | 75.0% | 33.3% |
| 1:4 | 20.0% | 80.0% | 25.0% |
| 1:5 | 16.7% | 83.3% | 20.0% |
| 2:3 | 40.0% | 60.0% | 66.7% |
| 3:4 | 42.9% | 57.1% | 75.0% |
| 3:5 | 37.5% | 62.5% | 60.0% |
| 2:5 | 28.6% | 71.4% | 40.0% |
| 4:5 | 44.4% | 55.6% | 80.0% |
| 1:9 | 10.0% | 90.0% | 11.1% |
| 1:10 | 9.1% | 90.9% | 10.0% |
Where you see this
Mixing concrete or paint, splitting profit between partners, and reading exam pass ratios all use the share-of-total version. Comparing two prices or sizes uses the A-to-B version.
Try it yourself. Get your own result in seconds with the free Ratio Calculator.
Open the Ratio CalculatorFrequently asked questions
What is 3:2 as a percentage?
3 is 60% of the total and 150% of 2.
What percentage is 1:4?
1 is 20% of the total, or 25% of 4.
More guides
Written and reviewed by the editorial team at Evavel Private Limited. Found an error? Email care@calculations.one.