Math · Percentage

Percentage Calculator

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Percentage Calculator

Choose a calculation type, enter your two numbers, then select Calculate.

Calculation type

Percentage (%)

Of this number

How these calculations work

This calculator finds a percentage of a number, works out what percent one number is of another, calculates a percentage increase or decrease, or compares two numbers. "What is X% of Y?" uses (X ÷ 100) × Y. "X is what percent of Y?" uses (X ÷ Y) × 100. "Percentage change from X to Y" uses ((Y − X) ÷ X) × 100 — a positive result is an increase, a negative result is a decrease. "Percentage difference between X and Y" uses |X − Y| ÷ ((X + Y) ÷ 2) × 100 — always a positive number, comparing the two values symmetrically rather than treating either one as the "original" (that's what "Percentage change" is for).

Examples

20% of 50 is 10. 15 is 30% of 50. Going from 40 to 50 is a 25% increase; going from 50 to 40 is a 20% decrease. The percentage difference between 10 and 20 is about 66.67%.

About these formulas

These are standard percentage formulas from elementary arithmetic — no external source citation is needed for them.

Related tools

More calculators are on the way — browse everything planned on the Home page.

Frequently asked questions

Can I use negative numbers?

Yes, wherever the formula stays mathematically defined — for example, a negative percentage or a negative starting value. The only undefined cases are dividing by a zero "whole" or a zero starting value, which this calculator flags clearly instead of guessing.

Why does the calculator say my input is invalid?

Either a field is empty or contains something other than a number, or the calculation would require dividing by zero — for example, asking what percent a number is of zero, or the percentage change starting from zero.