Percentage Calculator

Work out a percentage of a number, a percentage increase or decrease, or what percent one value is of another. Five common questions, one form — everything is computed in this browser tab.

Calculation

What do you want to find?
Your numbers are remembered in this browser, so a reload keeps them. Clear removes them.

Answer

Enter a value in both boxes to get an answer.

Private by design. This page has no backend. The maths is done by JavaScript on your own device — the numbers never leave this page.

The five calculations

All five pick a question, and each updates as you type. Commas in big numbers are ignored, so pasting “1,250.5” works as 1250.5, and answers are rounded to two decimal places for display.

Percent of

What is 25% of 5,000? The answer is 5,000 × 25 / 100. This is the form for discounts (“save 15% on 80”) and for slicing a quantity into shares.

Percent change

How much, as a percentage, did a value move between two points — a price, a salary, a population? From 5,000 to 6,000 is a 20% increase because 1,000 is one fifth of the starting value. A drop is shown with a minus sign. To stay intuitive when the starting value is negative, the change is measured against its absolute value.

What percent of

One value as a fraction of another: 15 out of 60 is 25% because 15 / 60 = 0.25. Useful for checkable progress bars, scores and share-of-market questions.

Increase / decrease by

Add a percentage onto a base (a price rise, a mark-up) or take it off (a sale, a pay cut). Increasing 5,000 by 25% gives 6,250; decreasing it by 25% gives 3,750. The result line always shows the absolute amount gained or lost as well, so the two modes are easy to compare side by side.

Rounding

Answers are rounded to two decimal places for display — for example 1/3 of 1,000 is shown as 333.33. The underlying value is kept to full precision before rounding, so these are display figures only and cannot drift between reloads.

Common uses

Checking sale prices and discounts, budgeting and tip mental-maths, reporting growth or decline, splitting results by proportion, and sanity-checking statistics you read elsewhere.

How to use the Percentage Calculator

  1. Choose the type of percentage calculation you need.
  2. Enter the two values.
  3. Read the result, which updates as you type.

Frequently asked questions

What calculations does it cover?

Percent of a number, percentage increase or decrease, and what percent one value is of another.

Can I work backwards to find the original value?

Yes. The increase and decrease modes let you find the starting or final value.

Does it round the answer?

Results are shown to a sensible number of decimal places, with the exact value available.