Percentage calculator

X% of a number, what percent one number is of another, percent change, increase and discount.

Result

15% of 200 is 30.

How to calculate percentages

X% of Y: multiply and divide by 100. 15% of 200 = 15 × 200 ÷ 100 = 30.

X is what % of Y: divide and multiply by 100. 30 of 200 = 30 ÷ 200 × 100 = 15%.

Percent change: (final − start) ÷ start × 100. From 100 to 125 is a 25% change.

Increase and discount: multiply by 1 + X/100 or 1 − X/100. $200 with 10% off = 200 × 0.9 = 180.

How do I find 10% of a number?

Divide it by 10. For example, 10% of 350 is 35. For 5%, halve that (17.50).

Does a 10% increase followed by a 10% discount get back to the start?

No. 100 increased by 10% is 110; 110 with 10% off is 99. The discount applies to a larger amount.

What is the difference between percent and percentage points?

If a rate goes from 10% to 12%, it rose 2 percentage points, but 20% in relative terms (2 ÷ 10).

How do I find the price before a discount?

Divide the sale price by (1 − discount). If $180 is the price after 10% off, the original was 180 ÷ 0.9 = $200.