Free Percentage Calculator
Work out percentages, increases and changes.
What is the Percentage Calculator?
Percentages come up constantly — a 20% tip, a 15% off sale, a test score, a 3% raise. The math isn't hard, but doing it in your head under pressure invites mistakes, especially when you're juggling percentage change versus percentage of a number.
This calculator handles the three questions people actually ask: what is X% of a number, X is what percent of Y, and how much did a value change in percent. Pick the mode, type the numbers, and read the answer.
Last updated: Aug 12, 2026
What does this tool do?
The tool covers the common percentage problems in one place so you don't have to remember which formula goes where.
In one mode it finds a percentage of a value; in another it tells you what percentage one number is of another; in the third it calculates the percent increase or decrease between two values.
Key features
Three modes
Percentage of a number, X is what percent of Y, and percentage change.
Instant results
Answers update as you type — no submit button.
Handles increase and decrease
Percentage change works for both directions.
No account
Open it and start calculating immediately.
Private
Calculations run in your browser.
Example
Common use cases
- Shoppers — Work out a sale price or how much a discount saves.
- Diners — Calculate a tip fast and fairly.
- Students — Turn a score into a percentage or check homework.
- Employees — See what a percentage raise adds to your pay.
- Investors — Measure the percent gain or loss on a position.
- Business owners — Compute margins, markups, and growth rates.
- Teachers — Convert marks into grades quickly.
- Anyone budgeting — Figure out what share of income goes to a category.
Benefits
- It removes the guesswork about which percentage formula to use.
- Answers appear instantly, so it's faster than a phone calculator.
- It covers change as well as simple percentages in one tool.
- Nothing you enter leaves your device.
Tips
- Percentage change uses the original value as the base, not the new one.
- To add a percentage, calculate the percent and add it to the original.
- For a discount, subtract the percentage amount from the price.
- A rise from 50 to 100 is a 100% increase, not 50%.
- Doubling is +100%; halving is −50% — the two aren't symmetric.
- Round only at the end to avoid compounding small errors.
- For tips, 15–20% of the pre-tax total is the usual range in the US.
- Percentage points and percent aren't the same — 5% to 6% is one point but a 20% relative increase.
Common mistakes to avoid
Using the new value as the base for percentage change
Fix: Always divide the difference by the original value.
Assuming a 50% cut and 50% rise cancel out
Fix: They don't — halving then adding 50% leaves you below where you started.
Confusing percentage points with percent
Fix: Going from 5% to 6% is one percentage point but a 20% relative increase.
Rounding too early
Fix: Keep full precision until the final step, then round.
How it works
- 1
Choose a mode
Percent of, is what percent, or change.
- 2
Enter values
Fill in the numbers.
- 3
Get the answer
The result updates instantly.
Frequently asked questions
Multiply the number by the percentage and divide by 100 — this tool does it instantly.
Yes — enter an old and new value to see the percent increase or decrease.
Multiply the number by the percentage and divide by 100. The tool does this instantly in the first mode.
Subtract the old value from the new one, divide by the old value, and multiply by 100. The change mode handles it for you.
Percentage points measure the raw gap between two percentages; percent measures the relative change between them.
Yes. Percentage change returns a negative number when the value drops.
Yes, with no account and no limits.
No. Everything is calculated locally in your browser.
Conclusion
Percentages get easier when you stop guessing which formula to apply. Use the right mode, read the answer, and jump to the discount or tip calculators when you need a purpose-built version.