Percentage Calculator
Each box below solves a different kind of percentage question. Fill in the numbers and press Calculate.
Percentage Calculator
Percentage formulas
A percentage is a number out of 100, so 35% means 35 ÷ 100 = 0.35. Every calculation on this page uses one of these four formulas:
| Question | Formula | Example |
|---|---|---|
| What is P% of X? | P ÷ 100 × X | 15% of 80 = 12 |
| A is what % of B? | A ÷ B × 100 | 18 of 24 = 75% |
| % change from A to B | (B − A) ÷ |A| × 100 | 50 → 65 = +30% |
| X increased or decreased by P% | X × (1 ± P ÷ 100) | 120 + 25% = 150 |
Everyday examples
Discounts
A $64 jacket at 30% off: 30% of 64 is $19.20, so you pay $64 − $19.20 = $44.80. You can also do it in one step with the bottom calculator: 64 minus 30% = 64 × 0.70.
Tips
An 18% tip on a $47.50 bill is 0.18 × 47.50 = $8.55, so the total is $56.05.
Test scores
Getting 42 questions right out of 48 is 42 ÷ 48 × 100 = 87.5%.
Price or pay changes
If rent goes from $1,450 to $1,595, the change is (1,595 − 1,450) ÷ 1,450 × 100 = 10% increase.
Percentage points vs. percent
When a rate moves from 4% to 5%, it rose by 1 percentage point, but by 25 percent (because 1 is 25% of 4). News reports about interest rates and polls usually mean percentage points.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 80 is 0.15 × 80 = 12.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 18 out of 24 is 18 ÷ 24 × 100 = 75%.
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value, then multiply by 100. Going from 50 to 65 is (65 − 50) ÷ 50 × 100 = a 30% increase.
Is percentage change the same as percentage difference?
No. Percentage change measures movement from a starting value, so the direction matters. Percentage difference compares two values with no starting point and divides by their average instead.
Why doesn't a 20% decrease undo a 20% increase?
Because the second percentage is taken from a different base. 100 increased by 20% is 120, but 120 decreased by 20% is 96, not 100.
See also
- Proportion Calculator: Solve A/B = C/D for the missing number, with steps.
- Ratio Calculator: Simplify ratios, convert to 1:n, and split a total in a ratio.
- GPA Calculator: Semester, weighted and cumulative GPA on the 4.0 scale.
- Compound Interest Calculator: Savings growth with monthly deposits and a year-by-year table.
Last updated: November 4, 2026