Percentage Calculator
Work out X% of a number, what percent one value is of another, or the percent change between two numbers.
How to use Percentage Calculator
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Pick a calculation
Choose one of the three modes: a percentage of a number, what percent one value is of another, or the percent change between two values.
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Enter your two numbers
Type the values into the labelled boxes. Each mode relabels the inputs so you always know which number goes where.
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Read the result and the sentence
The answer updates instantly, and a plain-English sentence underneath restates it in full so there’s no ambiguity.
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Copy it
Hit Copy to drop the result onto your clipboard, ready to paste into a document, spreadsheet or message.
Key features
- Three calculators in one: % of a number, “is what %”, and percent change
- Live results as you type — no “calculate” button
- Plain-English sentence that restates every answer in context
- Handles increases and decreases, with the direction spelled out
- Neatly rounded, copy-ready results with thousands separators
- 100% private and free — runs in your browser, no uploads or sign-up
About Percentage Calculator
A clean, instant percentage calculator for the three questions people ask most: “what is X% of Y?”, “X is what percent of Y?”, and “what’s the percent change from X to Y?”. Pick a mode, type two numbers, and the answer appears straight away alongside a plain-English sentence that spells it out — handy for double-checking discounts, tips, test scores, tax, commission, price increases and more. Results are tidily rounded and easy to copy. It all runs in your browser: no sign-up, no limits, nothing uploaded.
Last updated 2 June 2026.
Frequently asked questions
- How do I calculate X% of a number?
- Use the first mode and enter the percentage and the number. The formula is (percentage ÷ 100) × number — for example, 15% of 200 is (15 ÷ 100) × 200 = 30.
- How do I work out what percentage one number is of another?
- Use the “is what %” mode and enter the value and the total. The result is (value ÷ total) × 100 — for example, 50 out of 200 is (50 ÷ 200) × 100 = 25%.
- How is percentage change calculated?
- Percent change is (new − original) ÷ original × 100. A positive result is an increase and a negative result is a decrease — going from 120 to 150 is a 25% increase, while 150 to 120 is a 20% decrease.
- Why isn’t my percentage change symmetric?
- Because the change is always measured relative to the original value. Going up from 100 to 150 is a 50% increase, but coming back down from 150 to 100 is only a 33.3% decrease — the starting point is different each time.
- Can I use negative numbers or decimals?
- Yes. Decimals work everywhere, and negative numbers are supported. The only restriction is that the “total” (or the original value in percent-change) can’t be zero, since dividing by zero is undefined.
- Is anything sent to a server?
- No. Every calculation happens locally in your browser — nothing you enter is uploaded or stored, and it works offline once the page has loaded.