The three percentage questions, answered live
Every percentage problem is one of three shapes: finding a percentage of a number (discounts, tips, tax), finding what percent one number is of another (test scores, progress), or finding the change between two numbers (price increases, growth). Each has its own row above — type into any of them and the answer updates instantly.
Frequently asked questions
How do I calculate X% of a number?
Divide the percentage by 100 and multiply: 15% of 200 is (15 ÷ 100) × 200 = 30. The first row does this for you.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100: 30 out of 200 is (30 ÷ 200) × 100 = 15%. That's the second row.
How is percent change calculated?
(New − Old) ÷ |Old| × 100. Going from 100 to 125 is +25%; going from 125 to 100 is −20%. Note the asymmetry — the base changes.