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Calculators · Updated October 19, 2026

Percentage Calculator

You can work out a percentage of a number, find what percent one number is of another, or measure the increase or decrease between two values, with the formula shown beside every result.

Runs in your browserFree · No sign-up · No watermark
PercentagesRuns in your browser
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Everything runs locally in this tab. No file is uploaded while the tool loads.

This tool runs in your tab. Nothing is uploaded and no copy is stored.

How files are handled

At a glance

Works with
Percentages
Processing
In your browser
Price
Free, no account
Updated
October 19, 2026
All Calculators

About Percentage Calculator

Percentages turn up everywhere: a discount, a tip, an interest rate, a test score, a rent rise. Each of those is a slightly different question — a percentage of an amount, a share of a total, or a change between two values — and mixing them up is the usual reason a result looks wrong. This calculator separates the three questions so you always know which formula ran.

Every result is shown with the arithmetic behind it, including your numbers substituted into the formula, so you can check the answer or copy it into a spreadsheet with confidence. The result updates live as you type, negative values are handled explicitly, and a calculation that cannot have an answer is explained in plain language instead of showing Infinity.

What this tool does

The details that matter when you use Percentage Calculator for real work.

  • Three percentage modes

    Calculate X% of Y, express X as a percentage of Y, or measure the change from one value to another without reloading the page.

  • Working shown for every result

    Each answer lists the formula and the same formula with your numbers substituted, so the result can be checked line by line.

  • Live, forgiving input

    Results update as you type, thousands separators are accepted, and a trailing percent sign on a percentage field is ignored rather than rejected.

  • Negative values handled openly

    Percent change divides by the absolute value of the starting number, and the tool states that convention instead of hiding it inside the result.

  • One-click copy

    Copy the result to the clipboard as a plain number or percentage, ready for a document, invoice or spreadsheet cell.

  • Clear division-by-zero messages

    A whole of zero or a starting value of zero is reported in the result area rather than silently producing an infinite number.

How to use Percentage Calculator

No account, no installation — the whole job happens in this browser tab.
  1. 01

    Choose the question you are answering

    Pick X% of Y, X is what percent of Y, or increase / decrease, depending on what you already know.

  2. 02

    Enter the two numbers

    Type the values into the two fields; commas and a trailing percent sign are accepted. The result appears immediately.

  3. 03

    Read the result and the working

    The large number is the answer; under it the formula and your substituted numbers show exactly how it was reached.

  4. 04

    Copy the answer

    Press Copy result to put the formatted number on the clipboard for the field or document you are filling in.

  5. 05

    Reset for a new calculation

    Press Reset to clear both fields. Switching mode keeps the values, which is handy for re-reading the same pair of numbers a different way.

How this tool works

Works with
Percentages
Processing
Client-side, in your browser. Nothing is uploaded.
Requirements
Chrome, Edge, Firefox or Safari · JavaScript enabled

Limitations worth knowing

  • Percentage change from a zero baseline is undefined, and from a negative baseline it is ambiguous; the tool treats zero as undefined and divides by the absolute value otherwise.
  • Results are rounded for display to at most six decimal places, so very small or very large ratios may differ slightly from the exact fraction.
  • Only the three question types above are covered; compound percentage changes, tax-inclusive pricing and percentage points are separate calculations.

Privacy and file handling

All three percentage modes run in your browser with plain JavaScript. The numbers you enter are never uploaded, stored or logged, and no request is made to a server while you calculate. Closing the page clears everything.

Read the full privacy policy

Percentage Calculator FAQ

Short, direct answers to the questions people ask before using this tool.
What is the difference between the three percentage modes?
X% of Y finds an amount, X is what percent of Y compares a part with a whole, and increase or decrease measures the change between two values. Each uses a different formula, which is why the calculator asks which question you are answering first.
How do I calculate a percentage increase by hand?
Subtract the starting value from the new value, divide by the absolute value of the starting value, then multiply by 100. Going from 80 to 96 is (96 − 80) ÷ 80 × 100, which is a 20% increase.
Why does a percentage change from zero show an error?
Any number divided by zero is undefined, so a change from a starting value of zero has no meaningful percentage. Report the absolute difference instead, or treat the first non-zero value as the baseline.
Can I use negative numbers in the percentage calculator?
Yes. Percent of and percent ratio handle negatives directly, and percent change divides by the absolute value of the starting number, so a move from −50 to −25 is shown as a 50% increase rather than a confusing negative result.
Why does 15% of 200 show 30 and not 3,000?
Percent means per hundred, so 15% is 15 ÷ 100 = 0.15, and 0.15 × 200 = 30. Forgetting the division by 100 is the most common percentage mistake, and the working line below the result makes the step visible.
Does the percentage calculator round the result?
The result is printed to at most six decimal places and rounded only for display, and the working lines show those same displayed numbers. Press Copy result to take the displayed value for use elsewhere.
How do I add or remove a percentage from a price?
To apply a change, use X% of Y with the price as Y and add or subtract the answer. To find what change already happened between two prices, use increase or decrease with the old price first and the new price second.
What is the difference between percentage point and percent?
A percentage point is an absolute difference between two percentages, while percent is a relative change. A rate moving from 5% to 6% rises by one percentage point but by 20 percent; this calculator always reports the relative percent.
Are my numbers sent to a server?
No. All three modes run in your browser with plain JavaScript. The numbers you enter are never uploaded, stored or logged, and closing the page clears everything you typed.