Percentage Calculator
Calculate percentages, shares and percentage change in one place.
All three percentage questions, one tool
Percentage problems come in three shapes, and people constantly apply the wrong formula. 1) What is X% of Y? — multiply: Y × X ÷ 100. (15% of 200 = 30.) 2) X is what percent of Y? — divide: X ÷ Y × 100. (30 is 15% of 200.) 3) Percent change from X to Y? — (Y − X) ÷ X × 100. (200 → 230 is a 15% increase.) Enter your two numbers above and read off all the relationships at once.
Where this trips people up
Reverse discounts: a price of ₹850 after a 15% discount did NOT start at ₹850 + 15%. The original was 850 ÷ 0.85 = ₹1,000. Percentage points vs percent: going from 10% to 15% is a 5 percentage-point rise but a 50% relative increase — news headlines mix these up constantly. Sequential changes: +50% then −50% is not back to start; it's −25% overall.
Quick mental math tricks
10% = move the decimal one place. 5% = half of that. 1% = two places. 15% of anything = 10% + half of 10%. And X% of Y always equals Y% of X — 8% of 50 is easier as 50% of 8 = 4.
Frequently asked questions
How do I find the original price before a discount?
Divide by (1 − discount rate). After a 20% discount, a ₹800 price means the original was 800 ÷ 0.80 = ₹1,000 — not ₹800 + 20% (₹960).
What is the difference between percent and percentage points?
Going from 10% to 12% is a 2 percentage-point increase, but a 20% relative increase. Use points when comparing two percentages directly.
Why doesn't +10% then −10% return to the original?
Because the second change applies to a different base. 100 → 110 → 99. Sequential percentage changes multiply: 1.10 × 0.90 = 0.99.
How do I calculate a percentage increase between two numbers?
Subtract old from new, divide by the old value, multiply by 100. From 80 to 100: (100 − 80) ÷ 80 × 100 = 25% increase.