How it works
Every percentage question is one of three sums:
- What is X% of Y? — multiply Y by X ÷ 100.
- X is what percent of Y? — divide X by Y, then multiply by 100.
- Percentage change from X to Y — (Y − X) ÷ X × 100.
The one that trips people up is change. A price that rises 20% and then falls 20% does not return to where it started: 100 → 120 → 96. Percentage change is always measured against the starting number, so a rise and a fall of the same percentage are different amounts.
Examples
Worked examples:
- 18% of ₹2,499: 2499 × 0.18 = ₹449.82 — the GST on a typical electronics bill.
- 45 out of 60: 45 ÷ 60 × 100 = 75%.
- From 80 to 95: (95 − 80) ÷ 80 × 100 = +18.75%; going back from 95 to 80 is −15.8%.
For marks and weighted grades, the grade calculator handles the weighting for you.
Percentage Calculator: frequently asked questions
- How do I calculate a percentage of a number?
- Multiply the number by the percentage and divide by 100. 18% of 250 = 250 × 18 ÷ 100 = 45.
- How do I calculate percentage increase?
- Subtract the old value from the new one, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25%.
- How do I work out a discount?
- Multiply the price by (1 − discount ÷ 100). 25% off ₹1,999 = 1,999 × 0.75 = ₹1,499.25.
- What is the difference between percentage change and percentage difference?
- Percentage change measures from a starting value; percentage difference compares two values symmetrically using their average as the base.