To find X% of Y, multiply Y by X and divide by 100. For example, 25% of 200 = (25 / 100) × 200 = 50.

How do I calculate percentage increase?

Percentage increase = ((New Value − Original Value) / Original Value) × 100. For example, going from 80 to 100 is a 25% increase.

What is the percentage difference formula?

Percentage change = ((New − Original) / Original) × 100. A positive result is an increase; a negative result is a decrease.

How do I add a percentage to a number?

To add X% to Y, compute Y × (1 + X / 100). For example, adding 15% to 200 gives 200 × 1.15 = 230.

20% of 100 is 20. Formula: (20 / 100) × 100 = 20.

Percentage Calculator

Five instant calculators: find a percentage of a number, calculate increase or decrease, add or subtract a percentage. All results update as you type.

What is X% of Y?

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X is what % of Y?

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How to calculate percentages

A percentage expresses a number as a fraction of 100. The word comes from the Latin per centum, meaning "by the hundred." Understanding the five most common percentage operations covers virtually every real-world scenario — from tip calculations to financial growth rates.

1. What is X% of Y?

Divide X by 100 to convert it to a decimal, then multiply by Y. For example, 30% of 250: (30 / 100) × 250 = 75. This is the most common operation — used for tips, discounts, and tax calculations.

2. X is what percent of Y?

Divide X by Y and multiply by 100: (X / Y) × 100. For example, 45 out of 180: (45 / 180) × 100 = 25%. Useful for test scores, survey results, and market-share figures.

3. Percentage increase and decrease

Subtract the original from the new value, divide by the absolute original, and multiply by 100: ((New − Original) / |Original|) × 100. A positive result is a percentage increase; negative is a decrease. Going from 80 to 100 is a 25% increase; from 100 to 80 is a 20% decrease. Note that increases and decreases are not symmetric.

4. Adding a percentage to a number

Multiply the base by (1 + X / 100). Adding 15% to 200: 200 × 1.15 = 230. Common for price markups, salary increases, and VAT calculations.

5. Subtracting a percentage from a number

Multiply the base by (1 − X / 100). Subtracting 20% from 500: 500 × 0.80 = 400. Used for discounts, depreciation, and tax-inclusive pricing.

Percentage formula reference

Type	Formula	Example
X% of Y	(X / 100) × Y	25% of 80 = 20
X is what % of Y	(X / Y) × 100	20 / 80 × 100 = 25%
% increase/decrease	((New − Orig) / \|Orig\|) × 100	80 → 100: +25%
Add X% to Y	Y × (1 + X / 100)	200 + 15% = 230
Subtract X% from Y	Y × (1 − X / 100)	500 − 20% = 400

Percentage calculations in Python

All five operations in plain Python — no libraries required.

# 1. What is X% of Y? x, y = 25, 200 result = (x / 100) * y print(f"{x}% of {y} = {result}") # 25% of 200 = 50.0 # 2. X is what percent of Y? x, y = 45, 180 result = (x / y) * 100 print(f"{x} is {result:.2f}% of {y}") # 45 is 25.00% of 180 # 3. Percentage increase / decrease from X to Y original, new = 80, 100 change = ((new - original) / abs(original)) * 100 direction = "increase" if change >= 0 else "decrease" print(f"{original} → {new}: {abs(change):.2f}% {direction}") # 80 → 100: 25.00% increase # 4. Add X% to Y x, y = 15, 200 result = y * (1 + x / 100) print(f"{y} + {x}% = {result}") # 200 + 15% = 230.0 # 5. Subtract X% from Y x, y = 20, 500 result = y * (1 - x / 100) print(f"{y} - {x}% = {result}") # 500 - 20% = 400.0