Percentage Calculator
Free online Percentage Calculator to find percentages, percent change, and ratios instantly.
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The Percentage Calculator solves every common percentage problem instantly and without rounding errors: the percentage of a number, percentage increase or decrease, and what percent one value is of another. Whether you're working out a discount, a grade, a tip, or a growth rate, you get an accurate answer in a click — calculated in your browser.
Three Calculations, One Tool
Almost every percentage question reduces to one of three forms, and this tool covers all of them:
- Percent of a number — "What is 20% of 150?"
- Percentage change — "What's the increase from 80 to 100?"
- X is what percent of Y — "30 out of 150 is what percent?"
How to Use It
- Choose the calculation type that matches your question.
- Enter your numbers.
- Read the instant, precise result.
The Formulas Behind the Answers
| Question | Formula | Example |
|---|---|---|
| % of a number | number × (percent ÷ 100) | 20% of 150 = 30 |
| % change | (new − old) ÷ old × 100 | 80 → 100 = +25% |
| X is what % of Y | X ÷ Y × 100 | 30 of 150 = 20% |
Knowing the formula lets you verify the tool's output and apply the same logic anywhere — a useful skill when a quick estimate matters.
The Percentage Points Trap
One mistake causes more confusion than any other: conflating percentage points with percent change. If a rate rises from 10% to 15%, that is a 5 percentage point increase but a 50% relative increase. Headlines and reports frequently blur the two. When precision matters, always state which you mean.
Everyday Uses
- Shopping — calculate sale prices and how much you save.
- Dining — work out tips and split bills.
- School — convert scores into percentages and grades.
- Finance — interest, tax, commission, and returns.
- Analytics — measure growth, decline, and conversion rates.
Accurate and Private
Every calculation runs locally at full numeric precision, so you avoid the rounding errors of mental math while keeping your numbers entirely on your device. Use it as often as you need, free.
Frequently Asked Questions
How do I find a percentage of a number?
Multiply the number by the percentage expressed as a decimal. For example, 20% of 150 is 150 × 0.20 = 30. The calculator does this instantly, but understanding the formula helps you sanity-check results.
How do I calculate percentage increase or decrease?
Subtract the old value from the new value, divide by the old value, and multiply by 100. A positive result is an increase and a negative result is a decrease. The percentage-change mode handles this automatically.
How do I find what percent one number is of another?
Divide the first number by the second and multiply by 100. For example, 30 out of 150 is (30 ÷ 150) × 100 = 20%. This answers questions like 'what percent of the total did I score?'
What is the difference between percentage points and percent?
A change from 10% to 15% is a rise of 5 percentage points, but a 50% increase in relative terms. Mixing the two causes common errors, so be clear about which one a figure refers to.
Can it handle decimals and large numbers?
Yes. The calculator works with decimals, fractions of a percent, and very large numbers without rounding errors, so results stay accurate for finance, statistics, and everyday math alike.
Is the percentage calculator accurate?
Yes. Calculations run in your browser using full numeric precision, so you avoid the rounding mistakes that creep in with mental math or a basic calculator.
What are common real-world uses?
Discounts and sale prices, tips, tax, grades and test scores, commission, interest, and tracking growth or decline in any metric. Percentages appear everywhere money or comparison is involved.
Is this tool free?
Yes — free, instant, and unlimited, with no signup required.