Finance
Percentage Calculator
25% of 80 is 20. To find any percent of a number, multiply the number by the percent and divide by 100. This percentage calculator handles common percentage problems including percent-of, what-percent, and percent change.
Quick answer
To find X% of a number, multiply the number by X and divide by 100. For example, 15% of 80 is (80 × 15) ÷ 100 = 12.
What this tells you
- •To find X% of a number, multiply the number by X and divide by 100. For example, 15% of 80 is (80 × 15) ÷ 100 = 12.
- •Switch mode based on the question you need to answer.
- •Results support budgeting, discounts, and growth comparisons.
- •Percent-change mode assumes the original value is non-zero.
How to Use
- 1Select calculation mode.
- 2Enter the two numbers for that mode.
- 3Calculate to get the percentage result.
- 4Interpret positive or negative percent change as increase or decrease.
How It Works
Formula
Percent Of: (A/100) x B; Is What Percent: (A/B) x 100; Percent Change: ((New-Old)/Old) x 100Each mode applies the standard percentage formula for that question type.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Percent of a number
A20
B250
Result50
Common mistakes
- Using percent change mode with old value as zero
- Swapping A and B in what-percent calculations
- Interpreting negative percent change as growth
Frequently Asked Questions
Percent-of finds a portion of a value. Percent-change compares how much a value increased or decreased from an original value.
Yes. A negative result indicates a decrease from the original value.
When the denominator or original value is zero, percentage ratios are undefined.
15% of 80 is 12. Multiply 80 by 15, then divide by 100: (80 × 15) ÷ 100 = 12.
Subtract the old value from the new value, divide by the old value, then multiply by 100. Going from 50 to 60 is ((60 − 50) ÷ 50) × 100 = 20%.
Divide the part by the whole and multiply by 100. For example, 30 is (30 ÷ 150) × 100 = 20% of 150.
It estimates percentage calculator outputs using the visible inputs and formula assumptions on this page.