Pick the conversion you need, enter the numbers, and get the answer with the working. It turns fractions into percents, decimals into percents, percents into simplest-form fractions, and ratios into percentage shares.
Pick a question and enter the numbers
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Your answer
Your answer shows up here once you fill in the numbers.
What to enter
- Fraction to percent
- Enter the top and bottom numbers. The page divides, multiplies by 100, and also shows the decimal and the simplest form.
- Decimal to percent
- Enter the decimal. The page multiplies by 100 and shows the matching fraction when there is a short one.
- Percent to fraction
- Enter the percent. The page shows the fraction in its simplest form and the decimal.
- Ratio to percentages
- Enter the two parts. The page shows what share of the total each part is.
Worked examples
A fraction: 3 out of 8
You got 3 questions right out of 8 on a short quiz. What is that as a percent?
- Divide the top number by the bottom number: 3 ÷ 8 = 0.375.
- Multiply by 100 to get a percent: 0.375 × 100 = 37.5%.
3/8 is 37.5%. You can check it by going back: 37.5% of 8 is 3.
A decimal: 0.375
A calculator gives you 0.375. Turn it into a percent.
- Multiply the decimal by 100: 0.375 × 100 = 37.5.
- Add the percent sign: 37.5%. In other words, move the decimal point two places to the right.
0.375 is 37.5%. As a fraction it is 3/8.
A percent: 12.5%
What is 12.5% as a fraction?
- Divide the percent by 100 to get a decimal: 12.5 ÷ 100 = 0.125.
- Write it as a fraction over a power of 10 and cancel common factors: 1/8.
12.5% is 1/8. The page writes 0.125 as 125/1000, then cancels the common factors.
A ratio: 3 to 2
Two friends split a bill in the ratio 3 to 2. What percent does each pay?
- Add the parts to get the total: 3 + 2 = 5.
- Divide each part by the total and multiply by 100: 3 ÷ 5 × 100 = 60%.
- 2 ÷ 5 × 100 = 40%.
The ratio 3:2 is 60% : 40%. The two shares always add to 100%.
Common fractions as percents
These come up often in exams, so they are worth knowing without a calculator. Some do not end, so the page shortens them to four decimal places.
| Fraction | Decimal | Percent |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/3 | 0.3333 | 33.3333% |
| 1/4 | 0.25 | 25% |
| 1/5 | 0.2 | 20% |
| 1/8 | 0.125 | 12.5% |
| 1/10 | 0.1 | 10% |
| 2/3 | 0.6667 | 66.6667% |
| 3/4 | 0.75 | 75% |
| 3/5 | 0.6 | 60% |
| 7/8 | 0.875 | 87.5% |
Three conversions in your head
- To turn a decimal into a percent, move the point two places right. 0.45 becomes 45%.
- To turn a percent into a decimal, move the point two places left. 7% becomes 0.07.
- To turn a fraction into a percent, divide the top by the bottom, then move the point two places right.
How it is calculated
- For a fraction, divide the top number by the bottom number to get a decimal.
- Multiply the decimal by 100 and add a percent sign.
- To go back, divide the percent by 100 and write the decimal over a power of 10. Cancel common factors to get the simplest form.
- For a ratio, add the parts to get the total, then divide each part by the total and multiply by 100.
Percent = top ÷ bottom × 100
Decimal = percent ÷ 100
Share of a ratio = part ÷ (part 1 + part 2) × 100
Assumptions to keep in mind
- The simplest form is found by cancelling the biggest common factor. A decimal with more than six places is left as a decimal.
- Fractions that do not end, like 1/3, are shown shortened to four decimal places. The exact answer is 33.333…%.
- The ratio mode takes two parts. For a ratio with three parts, add them up and divide each by the total with the percentage calculator.
Mistakes that give the wrong answer
Dividing the bottom by the top
The percent is the top number divided by the bottom number. 3/8 is 3 ÷ 8, not 8 ÷ 3.
Forgetting to multiply by 100
0.375 is the decimal. The percent is 37.5%.
Adding the ratio parts wrongly
In a ratio of 3:2, the first part is 3 out of 5 parts, not 3 out of 2. Add the parts first.
Rounding too early
Round only the final answer. Rounding 1/3 to 0.33 before you multiply gives 33%, and the exact answer is 33.33%.
Questions students ask
How do I turn a fraction into a percent?
Divide the top number by the bottom number, then multiply by 100. For 3/8, that is 3 ÷ 8 = 0.375, and 0.375 × 100 = 37.5%.
How do I turn a decimal into a percent?
Multiply by 100, which means moving the decimal point two places to the right. 0.375 becomes 37.5%.
How do I turn a percent into a fraction?
Put the percent over 100 and cancel common factors. 12.5% is 12.5/100, which is 125/1000, which simplifies to 1/8.
How do I turn a ratio into percentages?
Add the parts to get the total, then divide each part by the total and multiply by 100. For 3:2, the total is 5, so the shares are 60% and 40%.
Can a percent be more than 100?
Yes. A fraction with a top number bigger than the bottom one, like 9/4, is above 100%. It means you have more than one whole.
