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Free Percentage Calculator Online

Calculate percentages five different ways: percentage of a number, percentage increase or decrease, what percent X is of Y, and percentage difference.

Runs entirely in your browser — your files are never uploaded to a server.

Last updated

This tool runs entirely in your browser. No data is sent to our servers.

How It Works

1. Choose Your File

Drag & drop or select the file you want to work with.

2. Processed in Your Browser

Everything happens locally on your device — your file is never uploaded anywhere.

3. Download Your Result

Get your finished file instantly, ready to save or share.

About Free Percentage Calculator Online

Percentage calculations come up constantly in everyday situations — figuring out a discount, calculating a tip, determining what percentage one number represents of another — and while the math itself is simple, doing it correctly in your head under time pressure (like at a checkout) is genuinely easy to get wrong.

This tool handles the common percentage calculation variants: finding what percentage one number is of another, finding a percentage of a given number, and calculating percentage increase or decrease between two values — covering the different ways “percentage” questions actually come up in practice.

A genuinely common point of confusion: percentage increase and percentage decrease aren’t simple inverses of each other. A 50% increase from 100 gives you 150, but a 50% decrease from 150 doesn’t bring you back to 100 — it gives you 75. This asymmetry is a real, common source of calculation errors, not a quirk of any particular tool.

Frequently Asked Questions

How do I calculate a percentage of a number?

Use the % of a number tab: enter the percentage and the number, and the result appears instantly. For example, 20% of 150 is 30. By hand, divide the percentage by 100 and multiply by the number.

How do I calculate a percentage increase or decrease?

Use the % increase or % decrease tab, enter the starting value and the percentage, and the tool returns the new value. For example, 100 increased by 15% is 115. These tabs apply a percentage to a number; they do not measure change between two values.

How do I calculate percentage increase between two numbers?

Use the formula (new minus old) divided by old, times 100. In this tool, open What % is X of Y and enter the difference (new minus old) as X and the old value as Y. A positive result is an increase and a negative result is a decrease.

What is the difference between percentage difference and percentage change?

Percentage change compares a new value with an original one and depends on direction. The % difference tab treats both values equally, dividing their gap by their average, so swapping the two numbers gives the same answer. Use change for before and after, difference for two comparable figures.

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