Percentage Calculator
Calculate "B% of A", "A as a percentage of B", and A increased or decreased by B%. Decimals and negative numbers are accepted.
How percentages are calculated
A percentage is a ratio out of 100: 1% is 0.01. This calculator handles the three most common questions.
- B% of A = A × B ÷ 100. For example, 12% of 2,500 is 300.
- A as a percentage of B = A ÷ B × 100. For example, 30 is 12% of 250. The calculator also shows how many times larger A is than B (A ÷ B).
- A increased or decreased by B% = A × (1 + B ÷ 100) for an increase, or A × (1 − B ÷ 100) for a decrease. For example, 2,500 increased by 12% is 2,800. The amount of change (B% of A) is shown as well.
Calculations use exact arithmetic, so there are no floating-point errors such as 0.1 + 0.2 ≠ 0.3. Negative numbers are rounded by their absolute value and the sign is restored afterward, so −2.5 and 2.5 round symmetrically.
Examples
- 15% of 80 = 12
- 45 is what percent of 60? = 75%
- 200 increased by 8.5% = 217
- 200 decreased by 8.5% = 183
- −50 as a percentage of 200 = −25%
Notes
- You can enter numbers with up to 12 digits before the decimal point and up to 6 decimal places. Commas as thousands separators (1,234.5) and a percent sign are accepted. Use a period as the decimal separator.
- "A as a percentage of B" cannot be calculated when B is 0.
- A percentage increase followed by the same percentage decrease does not return to the original number: 100 increased by 20% is 120, and 120 decreased by 20% is 96.
- To find how much a value changed from an old value to a new value, in percent, use the Percentage Change Calculator.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. To find 12% of 2,500, calculate 2,500 × 12 ÷ 100 = 300. Choose "B% of A" above, enter 2500 for A and 12 for B.
How do I find what percent one number is of another?
Divide the first number by the second and multiply by 100. For 30 out of 250, 30 ÷ 250 × 100 = 12%. Choose "A as a percentage of B".
How do I increase or decrease a number by a percentage?
Choose "A increased or decreased by B%", enter the original number as A and the percentage as B, and select Increase or Decrease. The result and the amount of change are both shown.