This percentage calculator has six parts, each answering one kind of percentage question as you type. Every answer shows the formula with your numbers in it, so you can check the working or copy it into a report. Numbers can include thousands separators, as in 1,250.
How to use the percentage calculator
Find the sentence that matches your question, such as What is X% of Y? or X is P% of what number?, and type into its boxes. The answer appears under the boxes straight away, with the working below it. Each calculator is separate, so you can keep six different questions on the screen at once.
- Commas, spaces and apostrophes in numbers are treated as thousands separators, and a % sign at the end is ignored.
- Use a dot for decimals. A decimal comma is read as a separator, so 7,5 becomes 75.
- In Add or take off a percentage, the first box switches between Take and Add.
Percentage formulas for each calculation
| Question | Formula | Example |
|---|---|---|
| Percent of a number | P ÷ 100 × Y | 20% of 150 = 30 |
| What percent X is of Y | X ÷ Y × 100 | 45 of 60 = 75% |
| Increase or decrease | (new − old) ÷ old × 100 | 80 to 100 = 25% increase |
| Add or take off P% | X ± X × P ÷ 100 | 15% off 1,200 = 1,020 |
| Find the whole | X ÷ (P ÷ 100) | 36 is 12% of 300 |
| Percentage difference | |X − Y| ÷ average × 100 | 40 and 50 = 22.2222% |
Adding 15% to 1,200 gives 1,380. The percentage increase calculator labels a negative change as a decrease, so 100 to 80 shows 20% decrease.
Change and difference are different questions
Percentage change has a direction. From 80 to 100 is a 25% increase, but from 100 back to 80 is a 20% decrease, because each is measured against its own starting value. Use change for prices, salaries and traffic, where there is a before and an after.
Percentage difference compares two values with no before or after, such as two quotes for the same job, so it divides the gap by their average. It gives the same answer whichever value you enter first.
Everyday percentage examples
Most real questions fit one of the six parts of the percentage calculator. A few common ones:
- Marks and grades: 42 out of 50 is 84%, and 412 out of 500 across five subjects is 82.4%. Use X is what percent of Y?
- A tip: 15% of 64 is 9.6. Use What is X% of Y?
- A sale price: take 15% off 1,200 to get 1,020.
- A spreadsheet: in Excel or Google Sheets,
=A2/B2formatted as a percentage gives what percent A2 is of B2, and=(B2-A2)/A2gives the change from A2 to B2. - Writing: keyword density is a percentage too. A phrase used 12 times in an 800-word article is 1.5% of the words. The Keyword Density Checker works it out for a whole page, and the guide on avoiding keyword stuffing explains what level is sensible. To get the word total first, paste the text into the Word Counter.
Mistakes the calculator helps avoid
- Adding a percentage and then removing it doesn't get you back to the start. 100 plus 10% is 110, and 110 minus 10% is 99.
- Removing tax from a price that includes it means dividing. A price of 1,180 that includes 18% GST was 1,000 before tax: put 1,180 and 118 into the find-the-whole calculator. Subtracting 18% instead gives 967.6, which is wrong.
- A fall needs a bigger rise to recover. After a 50% drop, a value has to grow 100% to return to where it was.
- Percentage points measure the gap between two percentages. A rate going from 5% to 6% has risen by one percentage point, which is a 20% increase in the rate.
Limits to know
The percentage calculator rounds answers to four decimal places, and very small results are shown in scientific notation. The calculator won't divide by zero, so a percentage change from 0 or a whole of 0 shows a message instead of a number. Nothing you type leaves the page. Other quick calculators and pickers are in Everyday Tools.
