Percentage Calculator
Solve common percentage questions: what is X% of Y, X is what percent of Y, percentage increase or decrease, and adding or subtracting a percentage.
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Percentage of a number
What is of ?
What percent is it?
is what % of ?
Percentage increase or decrease
From to
Add or subtract a percentage
±
How to use the percentage calculator
- Find the question that matches what you want to know. Each box solves one type of percentage problem.
- Type the two numbers. You can use decimals, and a comma or a point as the decimal separator.
- The answer appears immediately, together with the formula used, so you can check or repeat the calculation.
Features
Four calculators in one
Percentage of a number, what percent one number is of another, percentage change, and adding or subtracting a percentage.
Shows the formula
Every result includes the formula, useful for homework or double-checking.
Accurate decimals
Results are free of rounding glitches such as 0.30000000000000004.
Flexible number input
Accepts 1,234.5, 1.234,5, 12,5 and a trailing % sign.
Clear error messages
Explains why an answer can’t be calculated, for example a percentage of zero.
Common uses
- Work out discounts and sale prices
- Calculate tips, VAT or sales tax
- Measure growth or decline in prices, salaries or statistics
- Convert test scores to percentages
Related tools
Frequently asked questions
How do I calculate a discount?
Use “Add or subtract a percentage”: enter the price and the discount percentage. The result after “−” is the sale price. To see how much you save, use “Percentage of a number”.
How do I calculate percentage increase?
Use “Percentage increase or decrease”: enter the original value first and the new value second. A positive result is an increase, a negative one a decrease.
Why can’t I calculate a percentage change from zero?
Percentage change divides by the starting value. Any change from zero would be infinitely large, so it has no meaningful percentage.
Can I use negative numbers?
Yes. For percentage change with a negative starting value, the change is measured relative to its absolute size, so going from −50 to −25 is a 50% increase.
How precise are the results?
Results show up to six decimal places, and floating-point noise is removed. Round as appropriate for your use.
Percentage formulas
All four calculations use simple formulas you can also do by hand:
- X% of Y = X ÷ 100 × Y. Example: 15% of 80 = 12
- X as a percentage of Y = X ÷ Y × 100. Example: 12 of 80 = 15%
- Percentage change = (new − old) ÷ old × 100. Example: 80 → 100 = +25%
- Y plus X% = Y × (1 + X ÷ 100). Example: 80 + 15% = 92
Percentage change is not symmetric
A rise from 80 to 100 is a 25% increase, but a fall from 100 to 80 is a 20% decrease. The change is always measured relative to the starting value. That’s also why a 50% loss needs a 100% gain to recover.