How it works
The calculator applies the selected percentage formula instantly and formats the answer in plain language.
Switch modes for the three most common percentage questions.
Calculate percentages fast.
Solve common percentage questions including percent of a number, percentage share, and increase or decrease.
ResultReady
Result will appear here.
Practical examples
- Find 15% of 200, compare 30 as a percentage of 120, or calculate change from 80 to 100.
- Reverse a percentage change to estimate the original value before a discount or increase.
- Compare markup and margin from cost and selling price.
How to read the result
- Mode labels explain how X and Y are interpreted.
- Each result includes the formula used for that mode.
- Markup uses cost as the base; margin uses price as the base.
Limits and privacy notes
- Zero base values cannot be used for percentage-share or change calculations.
- Currency formatting is intentionally generic.
- Calculations run locally in the browser.
Pick the right mode
- Percent-of answers part of a number.
- Percent mode compares X against Y.
- Change mode compares old value to new value.
Markup vs margin
- Markup uses cost as the base.
- Margin uses price as the base.
- Reverse mode is useful for discounts and increases.
Avoid invalid bases
- Percentage share needs a non-zero comparison value.
- Change needs a non-zero start value.
- Formula lines show exactly what was calculated.