Percentage Calculator
Five percentage questions in one tool. Pick a mode and enter two numbers to get the answer instantly, with the steps shown.
Example: with Calculation What is A% of B? · Percent (A) 10 · Of value (B) 200 → Result: 20.00.
- Steps10.00% of 200.00 = 200.00 × (10.00 ÷ 100) = 20.00
Computed by the calculator below using its default values. Change any input to see your own numbers.
Proportion
🧠 Sharpen math skills with an app
Check it outThe five common questions
Percent of: 10% of 200 is 20. Is what percent: 20 out of 200 is 10%. Value after a change: 200 increased by 10% is 220, and decreased by 10% is 180. Percent change: going from 200 to 220 is a 10% increase, and a drop to 180 is a 10% decrease. Percent difference: comparing 200 and 220 without treating either as the “original” gives about 9.52% — a symmetric comparison, unlike percent change. Switch modes above to answer whichever you have; each mode shows its steps below the result.
How it’s calculated
Percent of: A ÷ 100 × B. Is what percent: A ÷ B × 100. Value after a change: B × (1 + A ÷ 100), where a negative A is a decrease. Percent change: (B − A) ÷ A × 100. Percent difference: |A − B| ÷ ((A + B) ÷ 2) × 100 — symmetric, so it doesn’t matter which value is entered first, unlike percent change which treats A as the original/base value.
Results update as you type and are estimates, not professional advice — verify important decisions with a qualified professional.
Common mistakes
- Confusing percentage points with percent change.
- Reversing which number is the base.
- Using percent change (directional) when you meant percent difference (symmetric), or vice versa.
Frequently asked questions
How do I find a percentage of a number?
Multiply the number by the percent and divide by 100. 15% of 80 = 80 × 15 / 100 = 12.
How is percent change calculated?
(New − Old) / Old × 100. Negative results mean a decrease.
Percentage points vs. percent?
Going from 10% to 12% is a 2 percentage-point rise but a 20% relative increase — they're different things.
What's the difference between percent change and percent difference?
Percent change is directional — it treats one value as the original and measures how far the other has moved from it, so going from 100 to 120 (+20%) is not the same size as going from 120 to 100 (−16.7%). Percent difference is symmetric — it compares two values with neither as the base, dividing their absolute difference by their average, so it gives the same result regardless of which value you list first.
How do I calculate a value after a percent increase or decrease?
Multiply the original value by (1 + the percent as a decimal) for an increase, or (1 − the percent) for a decrease. For example, $200 increased by 15% is 200 × 1.15 = $230, and $200 decreased by 15% is 200 × 0.85 = $170.