Quick answer
Use Percentage Calculator when you need a fast answer for percent-of math, percent increase or decrease, a discount, a markup, or a reverse percentage. Pick the mode first. Then type the numbers.
If the question is just a sale price, the Percent Off Calculator is faster. If you are adding tax after a price, use the Sales Tax Calculator.
Start with the mode
- Choose the percentage question that matches your problem.
- Type the numbers into the fields for that mode.
- Press Calculate percentage.
- Read the answer, formula line, and steps.
- Copy the answer if you need it in notes, homework, a message, or a spreadsheet.
Which mode should I pick?
Percent of a number: answers questions like 18% of 240.
What percent? answers questions like 25 is what percent of 200.
Percentage change: compares an original value with a new value.
Add or subtract percent: handles discounts, markups, tax, tips, and growth.
Reverse percent: works backward when you know the part and the percent.
Five examples that cover most searches
Examples from the percentage calculator
43.2
12.5%
27.5% decrease
150
200
Discounts, tips, tax, and markups
For a discount, choose Add or subtract percent, enter the original price, enter the discount percent, and choose Decrease. A $120 item with 25% off becomes $90 because 25% of 120 is 30, and 120 - 30 = 90.
For tax, tips, markup, or growth, use the same mode and choose Increase. The result shows the final value, and the formula line shows the amount added or subtracted.
Percent change mistake to avoid
Percent change needs a starting point. If a price drops from 160 to 116, the original value is 160. Avoid swapping the numbers. If you reverse them, you are asking how much 116 would need to rise to get back to 160.
The whole value cannot be zero in a what-percent question. The original value cannot be zero in a percentage-change question. For reverse percentages, the percent cannot be zero. "30 is 0% of what?" does not have one useful whole.
What the formula line means
The calculator shows the short math behind the answer. For percent-of questions, it uses value x percent / 100. For what-percent questions, it uses part / whole x 100. For percent change, it divides the change by the original value. Then it turns that result into a percent.
This matches the school idea of percent as "per 100." OpenStax explains percent this way. Khan Academy uses the same part, whole, increase, and decrease setup in percent practice.
Double-check before using the result
Double-check the mode, the starting value, and the sign on the result. A decrease should look like a decrease. A markup should make the number bigger. A discount should make it smaller.
Avoid using this page as the final rule for a store, class, tax form, or business policy. The calculator shows the math. The real rule still comes from the receipt, teacher, spreadsheet, or official policy.
History, privacy, and copying
Recent percentage answers stay visible in the current page while you work. This is useful when comparing discounts, prices, growth rates, or percentage changes. The tool keeps only a short list in the current browser tab. It is not sent to a server.
Copy answer copies the displayed answer to your clipboard so you can paste it into notes, homework, a spreadsheet, or a message.
Sources and limits
This guide checked the page against OpenStax percent basics, OpenStax percent applications, Khan Academy percentage-change practice, and Google's people-first content guidance.
The calculator is for checking math. That is the limit. It does not decide the real store price, tax rule, coupon rule, school grading rule, or business markup policy for you.