Pick a card
Find the calculation card you need.
Percent Calculator | Discount, Percent Change, Percent Of
Eight everyday percent calculations on one page — percent of a value, what percent, percent change, sale price, discount rate, and stacked discounts — each with the formula shown.
How to use
Enter numbers
Enter two numbers — commas are fine.
Read result
Read the result and the formula below it.
When to use this
Every percent problem comes down to choosing the base (the 100%). When in doubt, check what the denominator is.
Checking the real discount when a coupon stacks on a sale
Working out the discount rate from two prices
Measuring year-over-year growth in pay, sales, or prices
Finding what percent a score or progress represents
Percent formulas
Every formula comes down to ratio = part ÷ base × 100.
| Goal | Formula | Example |
|---|---|---|
| B% of A | A × B ÷ 100 | 15% of 200,000 = 30,000 |
| A is what % of B | A ÷ B × 100 | 36 is 30% of 120 |
| Percent change | (new − old) ÷ old × 100 | 50,000 → 65,000 = +30% |
| Sale price | price × (1 − rate ÷ 100) | 89,000 at 30% off = 62,300 |
| Discount rate | (price − sale) ÷ price × 100 | 129,000 → 99,000 = 23.26% |
| Stacked discount | 1 − (1 − a)(1 − b) | 20% then 10% = 28% |
Frequently asked questions
How do I calculate a percentage?
Divide the part by the whole and multiply by 100. 36 out of 120 is 36 ÷ 120 × 100 = 30%.
Do stacked discounts add up?
No. 30% off then 10% off is 37% off in total, because the second discount applies to the already-reduced price.
What is a percentage point?
The difference between two percentages. Going from 40% to 45% is a 5 percentage-point rise, or a 12.5% increase.