Percentages make fractions easy to compare: 17/20 and 41/50 are hard to rank at a glance, but 85% and 82% aren't. This calculator converts any fraction, improper fraction, mixed number or “score out of” into a percentage, shows the decimal in between, and lets you choose how many decimal places to keep.
How to use the fraction to percent calculator
- Enter the numerator — the part, such as the points you scored.
- Enter the denominator — the whole, such as the points possible.
- Add a whole number if you have a mixed number like 1 ½.
- Choose decimal places for rounding.
Fraction to percent formula
Mixed number: percent = (whole + numerator ÷ denominator) × 100
“Percent” means “per hundred”, so multiplying the decimal by 100 expresses the fraction as parts per hundred.
Worked examples
- Test score 17/20: 17 ÷ 20 = 0.85 → 85%
- 3/8 of a pie: 3 ÷ 8 = 0.375 → 37.5%
- 1/3: 0.3333… → 33.33% (rounded to 2 places)
- 7/4: 1.75 → 175%
Common fractions as percentages
| Fraction | Percent | Fraction | Percent |
|---|---|---|---|
| 1/2 | 50% | 1/8 | 12.5% |
| 1/3 | 33.33% | 3/8 | 37.5% |
| 2/3 | 66.67% | 5/8 | 62.5% |
| 1/4 | 25% | 7/8 | 87.5% |
| 3/4 | 75% | 1/10 | 10% |
| 1/5 | 20% | 1/20 | 5% |
| 2/5 | 40% | 1/25 | 4% |
| 1/6 | 16.67% | 1/50 | 2% |
Scores out of common totals
| Score | Percent | Score | Percent |
|---|---|---|---|
| 9/10 | 90% | 45/50 | 90% |
| 18/20 | 90% | 22/25 | 88% |
| 16/20 | 80% | 40/50 | 80% |
| 14/20 | 70% | 35/50 | 70% |
Mental shortcuts
- Denominators that divide 100 (2, 4, 5, 10, 20, 25, 50): scale to /100. 13/25 = 52/100 = 52%.
- Out of 10: add a zero. 7/10 = 70%.
- Halve and double: 3/8 is half of 3/4 (75%), so 37.5%.
Percent change versus percent of a whole
This calculator expresses a part as a percentage of a whole, which is the right tool for scores, shares and completion rates. It is not the same thing as percent change. If a price goes from 20 to 25, the new price is 25/20 = 125% of the old one, but the increase is 5/20 = 25%. When a problem says “what percent of” you want the conversion here; when it says “increase” or “decrease” you are measuring a difference against the starting value. The Percent Off Calculator handles discounts directly.
Rounding scores fairly
Schools often round a grade to a whole percent, but the rounding rule varies. A 17.5-out-of-20 paper is 87.5%, which becomes 88% under round-half-up and 88% under round-half-even as well, while 84.5% might go either way. If your instructor publishes a rule, follow it, and use the decimal-places box to see the unrounded value first. Keeping two decimal places in intermediate steps and rounding only the final figure prevents small errors from stacking up when you average several scores.
Need the decimal or a repeating decimal instead? Use the Fraction to Decimal Calculator. Working out a discount? Try the Percent Off Calculator.
Frequently asked questions
How do I convert a fraction to a percent?
Divide the numerator by the denominator and multiply by 100. 3/8 = 0.375, and 0.375 × 100 = 37.5%.
What is 17 out of 20 as a percentage?
17 ÷ 20 = 0.85, so 85%.
Can a percent be more than 100?
Yes. Any fraction bigger than 1 is over 100%. 7/4 = 1.75 = 175%, and a mixed number like 1½ is 150%.
What is 1/3 as a percent?
33.333…%, usually written 33.33% or 33⅓%.
Is there a shortcut when the denominator divides into 100?
Yes: scale the fraction to a denominator of 100. 7/25 = 28/100 = 28%, and 3/5 = 60/100 = 60%.