Percentage calculator
Work out percentages in seconds: X% of a number, what percent one number is of another, and the percent increase or decrease between two values.
Fix the highlighted fields to see your result.
How it is calculated
X% of N = X ÷ 100 × N
A of B = A ÷ B × 100
Change = (B − A) ÷ |A| × 100
Assumptions and limitations
- Results are rounded to two decimals for display.
- You cannot divide by zero: if B or the starting value is 0, that calculation has no result.
This tool is educational and provides estimates. It is not a credit offer or financial advice. Actual terms are set by each institution.
Everyday examples
- 18% tip on $45: mode 1 with 18 and 45 = $8.10.
- Test score: 42 correct out of 50: mode 2 = 84%.
- Your rent rose from $1,200 to $1,300: mode 3 = 8.33% increase.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. 15% of 200 = 0.15 × 200 = 30.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 30 out of 200 = 30 ÷ 200 × 100 = 15%.
How do I calculate percent change?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 80 to 100 = (100 − 80) ÷ 80 × 100 = 25% increase.
Why is a 20% increase followed by a 20% decrease not zero?
Because the second percentage applies to a different base. 100 + 20% = 120, and 120 − 20% = 96, a 4% net decrease.