Percentage formulas
- X% of Y = X ÷ 100 × Y. Example: 15% of 2,400 = 360.
- X as a percent of Y = X ÷ Y × 100. Example: 412 of 500 = 82.4%.
- Percentage change = (new − old) ÷ old × 100. Example: 800 to 1,000 is a 25% increase.
Percentage table
| Percent | of 200 | of 1,000 | of 2,500 | of 10,000 |
|---|---|---|---|---|
| 5% | 10 | 50 | 125 | 500 |
| 10% | 20 | 100 | 250 | 1,000 |
| 13% | 26 | 130 | 325 | 1,300 |
| 15% | 30 | 150 | 375 | 1,500 |
| 20% | 40 | 200 | 500 | 2,000 |
| 25% | 50 | 250 | 625 | 2,500 |
| 50% | 100 | 500 | 1,250 | 5,000 |
| 75% | 150 | 750 | 1,875 | 7,500 |
Marks to percentage examples
- 350 out of 500 = 70%
- 412 out of 500 = 82.4%
- 480 out of 600 = 80%
- 72 out of 100 = 72%
- 560 out of 800 = 70%
- 900 out of 1000 = 90%
Percent vs percentage points
If an interest rate rises from 10% to 12%, it went up by 2 percentage points, but by 20 percent of its old value. News reports and loan offers mix these up often. Use the increase/decrease calculator for the percent change, and plain subtraction for percentage points.
Common percentage mistakes
- Reversing a discount: if a price fell 20% to 800, the original was 800 ÷ 0.8 = 1,000, not 800 + 20% = 960.
- Adding percentages in a row: two 10% increases make 21%, not 20%, because the second one applies to the already-increased value.
- Using the wrong base: "A is 25% more than B" and "B is 25% less than A" are different statements. Always ask "percent of what?"
Everyday uses
Students use these to convert exam marks to percentages, shoppers to check discounts, and small businesses to measure month-on-month sales growth or price changes. For tax on a bill, the dedicated VAT calculator handles adding and removing VAT correctly.
Questions people ask
How do I calculate my marks percentage?
Divide the marks you obtained by the total marks and multiply by 100. For example, 412 out of 500 is 412 ÷ 500 × 100 = 82.4%. Use the second calculator above.
How do I calculate a discount?
Find the discount percentage of the price with the first calculator, then subtract it. 20% off 1,500 is 300, so you pay 1,200.
Is a 50% increase followed by a 50% decrease back to the start?
No. 100 increased by 50% is 150, and 150 decreased by 50% is 75. Percentage changes are always relative to the starting value of each step.
Updated · 26 Kartik 2083 BS