Percentage Calculator
The jacket is $80, the tag says 25% off, and you want the real price before you reach the till. You save $20. You pay $60. That is the whole job of a percentage: a part out of 100, turned into a number you can act on. Pick a mode below, type two numbers, and the working shows underneath.
Enter your numbers
Result
The Mistake That Costs People Money
Percent change compares a new value against the old one, so it has a direction; percent difference compares two values against their midpoint, so it has no direction — use change for before-and-after, difference for side-by-side. The other slip is the base, the number the percent is taken from. See How to Calculate Percentage for the full treatment of mistakes.
Every Mode, One Line Each
- % of a number: Result = Base × Percent ÷ 100
- X is what % of Y: Percent = X ÷ Y × 100
- Percentage increase: Increase % = (New − Old) ÷ Old × 100
- Percentage decrease: Decrease % = (Old − New) ÷ Old × 100
- Percent change: Change % = (New − Old) ÷ Old × 100 (the sign tells you up or down)
- Percent difference: Difference % = |A − B| ÷ ((A + B) ÷ 2) × 100
- % off: Sale price = Original price × (1 − Percent off ÷ 100); You save = Original price × Percent off ÷ 100
Seven Quick Checks
| Question | Working | Answer |
|---|---|---|
| What is 20% of 250? | 250 × 20 ÷ 100 = 5,000 ÷ 100 | 50 |
| 45 is what percent of 180? | 45 ÷ 180 × 100 = 0.25 × 100 | 25% |
| 80 rises to 100 | (100 − 80) ÷ 80 × 100 = 20 ÷ 80 × 100 | 25% increase |
The same three checks come up constantly: a tip at 15%, 18%, or 20% of the bill (the Tip Calculator splits it), a grade of 45 out of 180 marks (25%), and a price rise from $80 to $100 (25% increase). See How to Calculate Percentage for more worked examples.
Reading the Sign
A positive change means growth and a negative change means a drop. You cannot calculate a percent change from a starting value of zero, because division by zero has no answer — see How to Calculate Percentage.
Questions People Ask
What is the difference between percent change and percent difference?
Percent change compares a new value to the old one and keeps a sign: +25% means up, −25% means down. Percent difference compares two values to their midpoint and is always positive. Use change for before-and-after, difference for side-by-side comparisons.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, and multiply by 100.
How do I work out % off in a shop?
Multiply the original price by the discount and divide by 100 to get what you save, then subtract it from the price. See How to Calculate Percentage for worked examples.
What is 20% of 250?
50. Multiply 250 by 20 and divide by 100.
Can a percentage be more than 100%?
Yes. It just means the part is bigger than the base, as when something grows to more than double.
If percentages were a stepping stone: the Fraction Calculator turns fractions into percentages and back, the Ratio Calculator simplifies ratios and compares parts, the Average Calculator covers mean, median, and mode for any set of numbers, and the Tip Calculator works out tips and splits the bill. How to Calculate Percentage is the full step-by-step guide, and Percentage Increase and Decrease explains increase and decrease with examples. All Math Calculators · All Calculators