Percentage calculator

Do the four most common percentage calculations in one place: a share of a number, what percent one number is of another, percent change, and a number increased or decreased by a percentage. Use it for discounts, test scores, price changes, and growth rates.

Negative numbers and decimals are allowed.

How to use

Choose the type of calculation.
Enter values A and B. Each option shows where A and B go.
Read the result. Percent change shows + for an increase and − for a decrease.

How it works

B% of A = A × B ÷ 100.

A as a percent of B = A ÷ B × 100.

Percent change from A to B = (B − A) ÷ A × 100. A positive result is an increase and a negative result is a decrease.

A increased by B% = A × (1 + B ÷ 100). Use a negative B to decrease.

Example

15% of 200 is 30, and 30 is 15% of 200. Sales rising from 200 to 250 is a change of +25%, and falling from 200 to 150 is −25%.

A 30% discount on a price of 50 gives 35. Going back from 35 to 50 takes an increase of about 42.86%, not 30%.

Good to know

Percent change and percentage points are different. Use percentage points for the difference between two rates.
Raising and then lowering by the same percentage does not return the original value. Up 10% then down 10% leaves you 1% below where you started.

Frequently asked questions

How do I calculate a 30% discount?

Choose "A increased by B%" and enter the original price as A and −30 as B. A price of 50 becomes 35.

What is the difference between percent change and percentage points?

If a rate rises from 2% to 3%, it went up 1 percentage point but increased by 50%. This calculator's percent change is (B − A) ÷ A × 100.

How many decimals are shown?

Results are rounded to at most four decimal places.

Last updated: 2026-10-29