Percentage Calculator
This calculator covers the five everyday percentage questions: what X% of a number is, what percent one number is of another, what a value becomes after adding or subtracting a percent, and which number has the given value as its X%.
The formula behind every answer is printed next to the result, so you can copy the arithmetic into a spreadsheet or a report instead of trusting a black box.
Result
360
Formula: number × percent ÷ 100
Percentage formulas
- Percent of a number: number × percent ÷ 100. 15% of 2,400 is 360.
- Share as a percent: part ÷ whole × 100. 360 out of 2,400 is 15%.
- Add a percent: number × (1 + percent ÷ 100). 2,400 plus 15% is 2,760.
- Subtract a percent: number × (1 − percent ÷ 100). 2,400 minus 15% is 2,040.
- Find the whole: part ÷ percent × 100. If 360 is 15%, the whole is 2,400.
Doing percentages in your head
One percent is the number with the decimal point moved two places left. For 4,500 that is 45, so ten percent is 450.
Everything else is assembled from those pieces: 20% is two lots of 10%, 5% is half of 10%, and 15% is 10% plus 5%. Most shop-floor and invoice checks come down to adding two or three easy numbers.
Percentages of different numbers
| Percent | Of 1,000 | Of 7,500 | Of 42,000 |
|---|---|---|---|
| 1% | 10 | 75 | 420 |
| 5% | 50 | 375 | 2,100 |
| 10% | 100 | 750 | 4,200 |
| 15% | 150 | 1,125 | 6,300 |
| 20% | 200 | 1,500 | 8,400 |
| 25% | 250 | 1,875 | 10,500 |
| 50% | 500 | 3,750 | 21,000 |
Where percentages usually go wrong
- Percentages of different bases cannot be added: 10% of salary and 10% of a bonus are different amounts.
- Adding and then removing the same percent does not return the original: 100 plus 20% minus 20% is 96.
- A percent is not a percentage point: a rate moving from 5% to 7% rises by two points, which is a 40% increase.
- Stacked discounts of 20% and 10% come to 28%, because the second one applies to the already reduced price.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percent and divide by 100. For example, 15% of 2,400 is 2,400 × 15 ÷ 100 = 360.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. The number 360 is 360 ÷ 2,400 × 100 = 15% of 2,400.
How do I find the original number from a percentage?
Divide the known part by the percent and multiply by 100. If 360 is 15%, the original number is 360 ÷ 15 × 100 = 2,400.
What is the difference between a percent and a percentage point?
A percentage point is the gap between two percentage values. A rate rising from 5% to 7% gains two percentage points, which is a 40% increase.
Why does adding and subtracting the same percent shrink the number?
Because the subtraction applies to the larger figure. 100 + 20% = 120, and 120 − 20% = 96.
Updated: 2026-08-09