Percentage Calculator

Calculate percentages quickly with our free percentage calculator and percent calculator. This percentage calculator online tool makes it easy to calculate percentages, percentage change, percentage increase, and percentage decrease. Use the percent increase calculator, percent decrease calculator, and percentage difference calculator for everyday math, finance, business, schoolwork, discounts, and statistics. You can also calculate the percentage of a number and quickly calculate percentage values without manual formulas. Wondering how do I calculate a percentage, how do I calculate percentage increase, or what percentage is X of Y? Enter your numbers and get the answer instantly.

How to use the Percentage Calculator

Select the type of calculation.
Enter X and Y.
Read the answer instantly or press Calculate.

Percentage Calculator features and limits

Three common calculation modes
Validation for empty or invalid numbers
Limitation: percentage change from zero is undefined and is reported as an error.

How the Percentage Calculator works

The page applies the standard formulas: X × Y ÷ 100, X ÷ Y × 100, and (Y − X) ÷ |X| × 100.

Privacy and browser processing

Your input is processed locally in this page and is not uploaded or stored by Best Web Tools. Your hosting provider may still keep ordinary server logs for page requests.

Frequently asked questions

What is percentage change?

It measures how much a value rose or fell relative to its starting value.

Are results rounded?

Results are rounded to six decimal places.

What is 20% of 100?

20% of 100 is 20. Use the “X% of Y” mode with X as 20 and Y as 100.

How do I calculate percentage increase?

Use the change mode: subtract the old value from the new one, divide by the old value and multiply by 100. Going from 50 to 60 is a 20% increase.

How do I calculate percentage decrease?

The same change mode gives a negative result for a decrease. Going from 80 to 60 is a 25% decrease.

Browse all Calculators or return to the Best Web Tools homepage.

Why use the Percentage Calculator?

Discounts, tips, grades and growth figures all rely on percentages. Choosing the right mode matters: “20% of 50” and “20 is what percent of 50” are different questions, which is why the calculator separates them.