How to use the Percentage Calculator
Type into any row and the answer updates as you go. Percentage change uses (new − old) ÷ |old| × 100.
Frequently asked questions
How do I calculate a discount?
20% off 80 is 80 × 20 / 100 = 16, so you pay 64. Use the first row.
Why isn't +50% then −50% back to the start?
Because the second percentage applies to a bigger number: 100 → 150 → 75.