We have permanently closed Guest Posting on this site. Thank you for your contributions.

Percentage Calculator

Quickly work out any percentage — a percent of a number, what percent one number is of another, or the percentage change between two numbers.

Last updated: September 2026

15% of 200 is
30

Three percentage calculations in one

Percentages come up everywhere — tips, discounts, grades, taxes, and data. This calculator handles the three most common questions:

  • What is X% of Y? — e.g. 15% of 200 = 30.
  • X is what percent of Y? — e.g. 30 is 15% of 200.
  • Percentage change — the increase or decrease from one number to another.

The formulas

  • Percent of a number: (percent ÷ 100) × number.
  • Percent one number is of another: (part ÷ whole) × 100.
  • Percentage change: ((new − old) ÷ old) × 100 — a negative result means a decrease.

Frequently asked questions

Is this percentage calculator free?

Yes — completely free, no sign-up, and it runs entirely in your browser.

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. For example, 20% of 50 = (20 ÷ 100) × 50 = 10.

How do I find percentage increase or decrease?

Subtract the old value from the new value, divide by the old value, and multiply by 100. A negative answer is a decrease.

Can it handle decimals and negative numbers?

Yes — enter any values, including decimals and negatives, and the result updates instantly.

Related tools