Percentage Calculator

What is P% of X?

To find a percentage of a number: multiply the number by the percentage and divide by 100. y = (X × P) ÷ 100. Example: 20% of 150 = (150 × 20) ÷ 100 = 30. This is used for calculating discounts (20% off £50 = £50 × 0.20 = £10 off), tips (15% of £45 restaurant bill = £6.75), tax (20% VAT on £100 net = £20 tax), and interest charges. A quick mental shortcut: 10% is always the number divided by 10; 5% is half of 10%; 1% is the number divided by 100.

X is what % of Y?

To find what percentage one number is of another: divide the first number by the second and multiply by 100. P = (X ÷ Y) × 100. Example: 30 is what percentage of 150? Answer = (30 ÷ 150) × 100 = 20%. Used for calculating exam scores (26 correct out of 40 total = 65%), sale comparisons (product A costs £18, product B costs £24 — A is 75% of the price of B), and efficiency measurements (actual output 340 units vs target 400 = 85% of target achieved).

X is P% of what?

Y = (X × 100) ÷ P. Example: 30 is 20% of what = (30 × 100) ÷ 20 = 150. Useful when you know the result and the percentage, but not the original number.

Increase / Decrease by P%

Increase: Y = X × (1 + P/100). Decrease: Y = X × (1 − P/100). Example: 150 increased by 20% = 150 × 1.20 = 180. Used for price rises, salary increases, and VAT calculations.