Percentage Calculator

Calculate percentages, percent change and reverse percentages instantly — free online.

About

About the Percentage Calculator

Answers four common percentage questions instantly, including percent of a number, percent change and reverse percentage.

Shoppers use it to work out a discounted price, while sales and marketing professionals use it to find the percent change between two periods. It's one of many free calculators on Toolapt, and like every tool here, it's free to use with no sign-up and no limit on how many times you run it.

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Guide

Using the Percentage Calculator

  1. 1

    Step 1

    In the first box, type a percent and the number it's a percent of to see the answer instantly.

  2. 2

    Step 2

    In the second box, type two numbers to see what percent the first is of the second.

  3. 3

    Step 3

    In the third box, type a starting and ending number to see the percent change (increase or decrease).

  4. 4

    Step 4

    In the fourth box, type a number and the percent it represents to find the original whole number.

  • Answers all four calculations live as you type — no calculate button needed
  • Clearly labels a percent change as an increase or a decrease, not just a number
  • Catches divide-by-zero and other invalid inputs with a clear message instead of a wrong answer
  • Each of the four calculators works independently, so you can use just the one you need
  • Works entirely in your browser — no installs and no sign-up
  • Free to use, with no limit on how many times you run it
  • Fully responsive, so it works just as well on a phone as on a desktop

Shoppers

Shoppers use the Percentage Calculator for working out a discounted price or how much a sale actually saves.

Students

Students use the Percentage Calculator for checking percentage homework or working out a test score as a percentage.

Sales and marketing professionals

Sales and marketing professionals use the Percentage Calculator for finding the percent change between two periods, like month-over-month growth.

Anyone doing everyday maths

Anyone doing everyday maths uses the Percentage Calculator for a quick, reliable answer without reaching for a spreadsheet.

Examples

Percentage Calculator examples

3 worked examples

01

Percent of a number

15% of 200 is 30 — typed straight into the first calculator with no button to click.

02

What percent one number is of another

30 is 15% of 200 — the same relationship as the first example, checked from the other direction.

03

Percent change and reverse percentage

Going from 80 to 100 is a 25% increase, and 45 being 30% of a number means that number is 150.

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FAQ

Frequently asked questions

Quick answers to common questions about the Percentage Calculator.

What does the Percentage Calculator do?

It answers four common percentage questions: percent of a number, what percent one number is of another, percent change, and the reverse — what number a percentage came from.

Is the Percentage Calculator free to use?

Yes. It's free, with no sign-up, no watermark and no limit on how many times you use it.

Is my input safe when I use this tool?

Yes. The numbers you enter are processed entirely on your own device — nothing is sent to a server.

How is percent change calculated?

It's calculated as (new value − old value) ÷ old value × 100, and the result is labelled as an increase or a decrease depending on the sign.

What happens if I divide by zero?

The calculator shows a clear message instead of an answer whenever a calculation would need to divide by zero, such as a percent change starting from 0.

Do I need to click a button to see the answer?

No. Each of the four calculators updates its answer instantly as you type, with no separate calculate step.

Can I use the Percentage Calculator on my phone?

Yes. The page is fully responsive and works on mobile, tablet and desktop browsers alike.

Does the Percentage Calculator have any limitations?

It's built for everyday percentage questions. Extremely large or precise numbers aside, results are accurate and instant.

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Percentage Calculator

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