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Percentage Calculator

Find a percentage of a number, what percent one number is of another, percentage change, or increase and decrease a value by a percent.

%

The percent to take.

Result

10.0000

Percentage
20.00%
Of
50.0000
Result10.0000View results

Work out everyday percent problems: what is X% of Y, X is what percent of Y, X is Y% of what, percentage change between two numbers, and increase or decrease a value by a percent.

Formula

The core relationship is:

P × V1 = V2

P is the percent as a decimal (20% → 0.20), V1 is the original value, and V2 is the result. Rearrange to solve for any one of the three.

Percentage change compares a new value to a start:

change % = (new − start) ÷ start × 100

Increase / decrease applies a percent to a single number:

increased = value × (1 + P)
decreased = value × (1 − P)

A 10% decrease followed by a 10% increase does not return to the start — you end below the original because the increase is applied to a smaller base.

Examples

What is 20% of 50

0.20 × 50 = 10.

500 increased by 10%

500 × 1.10 = 550. Decreased by 10% is 500 × 0.90 = 450.

Frequently asked questions

How do I find a percentage of a number?
Convert the percent to a decimal and multiply. 20% of 50 is 0.20 × 50 = 10. That is the same as P × V = result, with P written as a percent.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 10 is 10 ÷ 50 × 100 = 20% of 50.
How is percentage change calculated?
Subtract the starting value from the new value, divide by the starting value, and multiply by 100. Going from 100 to 150 is (150 − 100) ÷ 100 = 50% increase.
What is the difference between increase and decrease by a percent?
Increase multiplies by (1 + P). Decrease multiplies by (1 − P). 500 increased by 10% is 550; decreased by 10% is 450.
Can the starting value be zero for percentage change?
No. Percentage change divides by the original amount, so a starting value of zero is undefined. Use a non-zero starting number.

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