How to use the Percentage Calculator
- Pick the calculation you need from the three boxes.
- Type your numbers — the answer appears instantly.
Percentage formulas
- X% of Y = Y × X ÷ 100
- X is what % of Y = X ÷ Y × 100
- % change from A to B = (B − A) ÷ A × 100
Example: a price that goes from 80 to 100 has increased by (100 − 80) ÷ 80 × 100 = 25%.
Percentage change vs percentage points
If an interest rate rises from 4% to 5%, it has risen by 1 percentage point but by 25 percent. Mixing up the two is one of the most common percentage mistakes.
Frequently asked questions
How do I calculate a discount?
Use “X% of Y” to find the discount amount, then subtract it from the original price. A 20% discount on 1,500 is 300, so you pay 1,200.
Why is a 50% drop followed by a 50% rise not back to the start?
Because the second percentage is applied to a smaller number. 100 → 50 (−50%) → 75 (+50%).