Percentage Calculator
What is X% of Y, percentage change, increase and more.
What is X% of Y?
15% of 200 = (15 ÷ 100) × 200
30
X is what % of Y?
(30 ÷ 200) × 100
15%
Percentage change from X to Y
(250 − 200) ÷ 200 × 100 — a increase
+25%
Increase / decrease Y by X%
200 × (1 + 10 ÷ 100)
220
Four ways to work with percentages
A percentage is simply a fraction out of 100. This page covers the four calculations people actually search for, each with its own formula:
What is X% of Y? Result = (X ÷ 100) × Y — e.g. a 15% tip on a ₹200 bill.
X is what % of Y? Result = (X ÷ Y) × 100 — e.g. what share 30 marks out of 200 total marks represents.
Percentage change from X to Y Result = ((Y − X) ÷ X) × 100, positive for an increase and negative for a decrease — e.g. a price moving from ₹200 to ₹250.
Increase or decrease Y by X% Result = Y × (1 ± X ÷ 100), using + to increase and − to decrease — e.g. adding a 10% service charge to a ₹200 bill.
How to use this calculator
- 1Pick the mini-calculator that matches your question.
- 2Type your numbers into the fields.
- 3The result and the exact arithmetic used both update instantly as you type.
- 4For the last calculator, toggle between Increase and Decrease.
Worked example
A shirt originally priced at ₹200 goes on sale, marked down to ₹150. Using "Percentage change from X to Y" with X = 200 and Y = 150: (150 − 200) ÷ 200 × 100 = −25%, a 25% decrease. To check it, use "Increase / decrease Y by X%" with Y = 200, X = 25, mode Decrease: 200 × (1 − 25 ÷ 100) = 150 — the two calculators agree.
Frequently asked questions
›Why is percentage change different from a simple percentage of?
Percentage change measures how much a value moved relative to its starting point, using ((new − old) ÷ old) × 100. A plain "X% of Y" calculation just extracts a fraction of a single number — there's no before/after comparison involved.
›If a price increases 25% then decreases 25%, do I end up back where I started?
No. A 25% increase on 200 gives 250, but a 25% decrease on 250 gives 187.5, not 200 — because the second percentage is taken from a different (larger) base. Percentage increases and decreases are only reversible when applied to the same starting value.
›What does a negative percentage change mean?
It means the value decreased. This calculator's "Percentage change from X to Y" shows a negative result and labels it a decrease whenever Y is smaller than X, and a positive result labelled an increase whenever Y is larger.
›Can I use decimals or negative numbers?
Yes — every field accepts decimals, and the increase/decrease and change calculators work correctly with negative starting or ending values too.
›Is this specific to any currency?
No. The math is entirely unitless — it works the same whether you're calculating a discount in rupees, a score out of marks, or any other pair of numbers.