Percentage Calculator
Work out percentages, percent change, and discounts on one page.
Percent of a number
100 × 15% = 15
What percent
30 ÷ 100 × 100 = 30%
Percent change
(125 − 100) ÷ 100 × 100 = +25%
Up 25
Increase or decrease
100 × (1 − 15%) = 85
Down 15
Percentage Calculator
This percentage calculator handles the four percentage questions people ask most, on one page. Change any number and the result and formula update right away.
B% of A = A × B ÷ 100
A out of B as a percent = A ÷ B × 100
Percent change = (new − starting) ÷ starting × 100
A increased by B% = A × (1 + B ÷ 100)
How to use
- Type numbers into the calculation you need. There is no Calculate button; results appear as you type.
- In Increase or decrease, click a discount or tip rate to fill in the percent and direction.
Key terms
Percent vs. percentage point
A percentage point is the plain difference between two percentages. A percent change compares that difference with the starting percentage.
| Example | Percentage points | Percent |
|---|---|---|
| Interest rate 2% → 3% | Up 1 point | Up 50% |
| Vote share 40% → 30% | Down 10 points | Down 25% |
Percent change
How much a value grew or shrank, as a share of where it started. If the starting value is 0, there is nothing to divide by, so percent change is undefined.
Why +10% and then −10% doesn’t get you back
The second step is a percentage of the new, larger number.
100 × 1.1 = 110 → 110 × 0.9 = 99
To get back to 100 you need to take 10 off 110, which is only about 9.09% of 110.
10 ÷ 110 × 100 ≈ 9.09%
FAQ
How do I calculate a tip?
Multiply the bill by the tip rate. A 15% tip on $80 is 80 × 0.15 = $12, so the total is $92. Click Tip 15% in Increase or decrease to see the total.
Is 30% off and then an extra 20% off the same as 50% off?
No. The extra 20% comes off the already reduced price, so you pay 0.7 × 0.8 = 0.56 of the original price. That is 44% off.
How do I find the price before sales tax?
Divide the total by 1 plus the tax rate. With a 7% tax, a $53.50 total is 53.50 ÷ 1.07 = $50 before tax. Sales tax rates vary by state and city.
Are my numbers saved?
No. Nothing is saved or sent to a server. All calculations happen in this browser.