Ratio to Percentage Calculator
Convert a ratio into percentage shares of the whole.
What the Ratio to Percentage Calculator does
To turn a ratio into percentages, add the parts to get the whole, then express each part as a fraction of that whole times 100. The percentages always sum to 100%.
Formula
Share % = Part ÷ (Sum of all parts) × 100
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| First part | number | Yes | — |
| Second part | number | Yes | — |
| Third part (optional) | number | Optional | — |
How to use it
- Enter First part and Second part.
- Optionally add Third part (optional).
- Select Calculate.
Worked example
Profits are split 3 : 2 between two partners.
- First part
- 3
- Second part
- 2
Total 5 parts, so 60% and 40%.
Reading the result
- The parts of a ratio always convert to percentages summing to 100, because each is measured against their total.
- A ratio of 1:3 is 25% and 75% — not 33% and 67%. The first number is one part out of four, not one part per three.
Common mistakes
- Treating a ratio as a fraction of the other part rather than of the whole, which is what turns 1:3 into a mistaken 33%.
- Expecting rounded percentages to add to exactly 100. Rounding each part independently can leave a point unaccounted for.
Frequently asked questions
Why do my percentages not add to exactly 100?
Rounding. Each share is rounded independently, so the displayed values can be off by a fraction of a percent.