How to Calculate Percentage

Q: What is the formula for percentage?

Percent of a number is (percent / 100) x number. X as a percent of Y is (X / Y) x 100. Percentage change is ((new - old) / old) x 100.

Working out a discount, a tip, or how much a value has grown? This guide shows you how to calculate percentage for free, with the formulas explained — no software, no upload, no sign-up.

When Do You Need a Percentage Calculator?

Working out a discount or tax on a price
Checking what percent one number is of another, like a test score
Calculating percentage increase or decrease, like a price change
Solving percentage problems quickly without doing math by hand

How to Calculate Percentage — Step by Step

Open the Percentage Calculator

Go to MyPDFEasy Percentage Calculator — works in any browser, no installation required.

Choose Your Calculation

Pick from three calculators: percent of a number, what percent X is of Y, or percentage increase/decrease.

Enter Your Numbers

Type in the values for the calculation you chose.

Get the Result

Click Calculate to see the answer instantly.

Percentage Formulas Explained

Percent of a number: (percent ÷ 100) × number — for example, 20% of 150 = (20 ÷ 100) × 150 = 30.
X as a percent of Y: (X ÷ Y) × 100 — for example, 30 is what percent of 120? (30 ÷ 120) × 100 = 25%.
Percentage change: ((new − old) ÷ old) × 100 — positive for an increase, negative for a decrease.

💡 Pro Tip: For a quick discount estimate, calculate 10% of the price first, then multiply or divide that number to get any other percentage.

％ Calculate a Percentage Now

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Frequently Asked Questions

How do I calculate a percentage of a number?

Enter the percentage and the number, for example 20% of 150, and click Calculate. Completely free.

How do I find what percent one number is of another?

Enter both numbers, for example 30 is what percent of 120, and it returns the percentage.

How do I calculate percentage increase or decrease?

Enter the original and new values, and it shows the percentage change, positive for an increase and negative for a decrease.

What is the formula for percentage?

Percent of a number is (percent ÷ 100) × number. X as a percent of Y is (X ÷ Y) × 100.