Percentage Calculator
Work out percentages fast: what is X% of a number, what percent one number is of another, and the percentage change between two values.
A simple, accurate percentage calculator for everyday math. It answers the three questions that come up again and again: what is X% of a number, what percent one number is of another, and by how much a value changed from old to new. It is useful for students checking grades, marketers reviewing conversion rates, business owners tracking margins, and anyone who wants a quick answer without opening a spreadsheet. Every calculation runs in your browser only. No number is sent to a server and nothing is stored. The result updates instantly as you type, and you can copy it with one click into any other app.
How to use this tool
- 01Choose a calculation typePercent of a number? What percent one number is of another? Or the percentage change between two values?
- 02Enter the valuesType the relevant numbers into the fields. Decimals are supported.
- 03Get an instant resultThe result updates in real time. Copy it with one click.
When is this useful?
- Working out a tipA bill of 320 and you want to add a 12% tip. Use "Percent of a number" with 12 and 320 to get 38.4.
- A test scoreYou answered 73 of 85 questions correctly. The "What percent" mode gives 85.88%, the exact score before rounding.
- Tracking campaign performanceA campaign brought 1,240 leads from 28,500 impressions. The conversion rate is 4.35%, a number you can compare to a benchmark.
- A raise in payPay went from 12,500 to 13,750. The change is +10%, exactly what you discussed in a review.
- Progress to a targetA monthly sales target of 50,000. By mid-month you have sold 21,500, so you are at 43% of the target.
- Discounts and couponsA product at 289 with a 15% discount saves 43.35. For shopping deals, try our discount calculator.
Examples
- 20% of 250Choose "Percent of a number", enter 20 then 250. The result: 50.
- A test with 87 correct out of 100Choose "What percent", enter 87 then 100. The result: 87%.
- A price rose from 100 to 130Choose "Percentage change", enter 100 then 130. The result: +30%.
- A value dropped from 58.40 to 49.20In percentage-change mode this is a decrease of 15.75%, handy for tracking an investment.
Tips for a better result
- Use decimalsIf you are working with a precise rate (such as 1.5% or 8.25%), enter the value as is, without rounding.
- Check in both directionsIf 20% of 250 gave you 50, check the reverse: 50 out of 250 should give 20%. If it does not, there is an input error.
- Tell percentage points apart from percentIf a rate grows from 5% to 7%, that is a rise of 2 percentage points, but a 40% relative increase. The difference matters in any report.
- Percentage change depends on directionA rise from 100 to 150 is 50%, but going back from 150 to 100 is only a 33.3% drop. Always note which number is the base.
How a percentage works, the basics
A percent is a part of one hundred. When you say 25% you mean 25 out of 100, or 0.25. Every percentage calculation comes down to multiplying or dividing by that number. The basic formula: to get a percent of a number, multiply the number by the percent and divide by 100. For example, 25% of 200 = 200 × 25 ÷ 100 = 50.
Three calculation types, when to use each
Percent of a number: you know the base and the percent, and you want the result. Example: "What is 18% of 3,500?" What percent: you have two numbers and want the ratio between them as a percent. Example: "47 out of 62 is what percent?" Percentage change: you have a before value and an after value, and you want to know how much it changed. Example: "The price was 89 and rose to 103, what is the percent increase?"
Common mistakes with percentages
The most common mistake is thinking that if something rises 50% and then falls 50%, you return to the same value. Not true. 100 grows to 150, then a 50% drop reaches 75. The reason: each percent is calculated on the new base, not the original. A second mistake is confusing percentage points with relative percent. If a rate went from 3% to 4%, it rose by one percentage point, but that is a 33% relative increase.
Privacy
The calculator runs entirely in your browser. No number is sent to a server, no history is kept, and no signup is needed. Close the page and all the data is gone.
Frequently asked questions
What is the difference between "Percent of a number" and "What percent"?
"Percent of a number" answers "what is X% of Y?", so you have the percent and the base. "What percent" answers "X is what percent of Y?", so you have two numbers and want the ratio between them.
How is percentage change calculated?
The formula is ((new value − old value) / old value) × 100. A positive value is an increase, a negative one is a decrease. Note that the base is always the old value, not the new one.
Is my data stored on a server?
No. The calculation runs in your browser only. No upload, no logs, no saving.
If I go up 20% and down 20%, do I return to the same value?
No. 100 increased by 20% becomes 120. A 20% drop on 120 is 96, not 100, because each percent is calculated on the base at that moment.
What is a percentage point?
A percentage point is the direct difference between two percentages. If a rate went from 4% to 5%, it rose by one percentage point, or a 25% relative increase. Both are correct, but they describe different things.
Can I use decimals?
Yes, in both the base value and the percent itself. For example, 8.25% of 1,734.50 is calculated exactly.
How do I calculate a percent when the base is zero?
Mathematically, dividing by zero is undefined. If the old number is 0, percentage change cannot be calculated, and a different measure is needed. The calculator shows nothing in that case.