How do you calculate X% of Y?

Divide X by 100, then multiply by Y. Formula: (X ÷ 100) × Y. Example: 25% of 200 = (25 ÷ 100) × 200 = 50.

How do you calculate percentage change?

Percentage change = ((new value − old value) ÷ old value) × 100. Example: from 80 to 100 = ((100 − 80) ÷ 80) × 100 = +25%. A negative result means a decrease.

What is X as a percentage of Y?

(X ÷ Y) × 100. Example: 15 out of 60 = (15 ÷ 60) × 100 = 25%.

(15 ÷ 100) × 80 = 12. Use the calculator above for any X% of Y combination instantly.

How do you add a percentage to a number?

Multiply by (1 + percentage/100). Adding 20% to 150 = 150 × 1.20 = 180. Subtracting 20% = 150 × 0.80 = 120.

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Percentage Calculator

What's X% of Y? Get the answer instantly.

Percentages show up everywhere — taxes, discounts, interest rates, tip amounts, grade curves. The math is always one of three things: finding a percentage of a number, finding what percentage one number is of another, or calculating how much something changed. Pick the right mode above and you're done in one step.

25% of 200

Remaining (100−X)%: 150
Doubled: 100

25% of 200 = (25 / 100) × 200 = 50

The three percentage calculations everyone needs

Most percentage confusion comes from mixing up which question you're actually asking.

X% of Y: 'What is 15% of $80?' → (15/100) × 80 = $12. Used for tips, tax, discounts.
X is what % of Y: '15 out of 60 is what percent?' → (15/60) × 100 = 25%. Used for test scores, ratios, market share.
% change from X to Y: 'Price went from $80 to $100 — how much did it increase?' → ((100−80)/80) × 100 = +25%. Used for price changes, growth rates, salary comparisons.

Common percentage mistakes

The biggest one: confusing percentage points with percent change. An interest rate rising from 4% to 6% is a 2 percentage point increase but a 50% increase in rate. These sound very different for good reason — they measure different things.

A price that went up 25% and then came back down 25% is not back to its original level. Up 25% then down 25%: $100 × 1.25 × 0.75 = $93.75. Percentages are multiplicative, not additive.

FAQ

How do you calculate X% of Y?: Divide X by 100, then multiply by Y. Formula: (X ÷ 100) × Y. Example: 25% of 200 = (25 ÷ 100) × 200 = 50.
How do you calculate percentage change?: Percentage change = ((new value − old value) ÷ old value) × 100. Example: from 80 to 100 = ((100 − 80) ÷ 80) × 100 = +25%. A negative result means a decrease.
What is X as a percentage of Y?: (X ÷ Y) × 100. Example: 15 out of 60 = (15 ÷ 60) × 100 = 25%.
What is 15% of 80?: (15 ÷ 100) × 80 = 12. Use the calculator above for any X% of Y combination instantly.
How do you add a percentage to a number?: Multiply by (1 + percentage/100). Adding 20% to 150 = 150 × 1.20 = 180. Subtracting 20% = 150 × 0.80 = 120.