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Percentage Calculator

The three percentage questions everyone asks, in one tool. Pick a mode and type two numbers.

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Common questions

How do I calculate a percentage of a number?

Multiply the number by the percent divided by 100. So 20% of 150 is 150 × 0.20 = 30.

How do I calculate percent change?

Subtract the old value from the new value, divide by the old value, then multiply by 100. Going from 80 to 100 is (100 − 80) ÷ 80 × 100 = a 25% increase.

Why isn't a 50% loss undone by a 50% gain?

Because the base changes. Drop $100 by 50% and you have $50; gaining 50% of $50 only gets you to $75. You'd need a 100% gain to break even — a useful thing to remember about investment losses.