Everyday math · instant
Percentages, without the guesswork.
Work out a percentage of a number, compare two numbers, measure change, or add a markup or discount. All four modes in one calculator.
What do you want to work out?
Pick a mode, then change the numbers.
15% of 200
30
Calculated instantly in your browser.
Where this helps
The percentage problem you actually have.
Percentages show up in discounts, tips, interest, test scores, pay rises and nutrition labels. The maths is simple, but the wording around it often is not.
- • A jacket marked 30% off at $120.
- • A salary rising from $52,000 to $58,000.
- • A price going from $80 down to $60.
- • A 15% tip on an $86.40 restaurant bill.
What does “percent” actually mean?
Percent means “per hundred.” Fifteen percent is 15 out of every 100, or 0.15. To take a percentage of a number, multiply by the percentage and divide by 100.
How do I calculate a discount?
Use the “Add or subtract a %” mode and choose Decrease. For example, 25% off an $80 item gives $60. The calculator shows the adjusted value directly.
What is the difference between percent and percentage point?
A percentage point is the direct difference between two percentages. Going from 10% to 12% is a rise of 2 percentage points, but a 20% relative increase. The change mode measures relative change.
Why does a 20% increase not cancel a 20% decrease?
Because each percentage applies to a different base. A 20% fall from 100 leaves 80, and a 20% rise from 80 gives 96, not 100.
Can I use decimals and large numbers?
Yes. The calculator accepts decimals, negative values for change calculations and large numbers with or without commas. Results are rounded to two decimal places for display.
How does percentage change handle negative starting values?
The change mode divides the difference by the absolute value of the starting number, so the sign always reflects whether the value moved up or down. Percentage change from a negative base is inherently ambiguous, so treat the result as a magnitude plus direction.
Is the calculator free and private?
Yes. It needs no account and runs entirely in your browser. The values you enter are not sent to simplytools.us or any third party.