General & Math

Percentage calculator

Understand a discount, compare a part to a whole, or measure how a number changed. Choose one of four calculations and get a clear result without sending your numbers to a server.

MAKE IT SIMPLE

Result

Worked examples

Original price 250, discount 15%

Final price 212.5 · You save 37.5

250 × (1 − 15 ÷ 100) = 212.5. Savings are 250 × 15 ÷ 100 = 37.5.

Amount 250, rate 15%

37.5

250 × 15 ÷ 100 = 37.5. A 15% discount removes 37.5 from the original price.

Part 18, whole 60

30%

18 ÷ 60 × 100 = 30. The part represents three tenths of the whole.

Original 80, new 100

+25%

(100 − 80) ÷ |80| × 100 = 25. The increase is relative to the original value.

Questions & answers

How are negative original values handled?

Change uses the absolute original value as its denominator. Moving from −80 to −60 gives +25%. This convention describes direction consistently; it is not an investment-return rule.

Can I calculate a percentage change from zero?

No. Division by zero is undefined. Use an absolute difference instead of a percentage when the original value is zero.