Percentage Calculator
Calculate percentages quickly. Find what percent of a number, percentage difference, or increase/decrease by a percentage.
How It Works
X% of Y: Multiply the number by the percentage divided by 100. For example, 25% of 200 = 200 × (25/100) = 200 × 0.25 = 50.
X is what % of Y: Divide the part by the whole and multiply by 100. For example, 50 is what % of 200? = (50/200) × 100 = 25%.
Percentage change: Subtract the old value from the new, divide by the old value, and multiply by 100. A positive result is an increase; negative is a decrease.
Increase/decrease: Multiply the original by the percentage (as a decimal), then add or subtract from the original. 100 + 20% = 100 + (100 × 0.20) = 120.
Frequently Asked Questions
How do I calculate percentage in my head?
For 10%, move the decimal one place left (10% of 250 = 25). For 5%, halve the 10% result. For 1%, move decimal two places left. Combine these for other percentages: 15% = 10% + 5%, 25% = 10% + 10% + 5%.
Why does a 50% decrease then 50% increase not return to the original?
Because each percentage is calculated from a different base. $100 - 50% = $50. Then $50 + 50% = $75, not $100. The increase percentage applies to the reduced amount. To return to original, you'd need a 100% increase.
What's the difference between percentage points and percent?
Percentage points are the absolute difference between percentages. If rates go from 5% to 7%, that's 2 percentage points but a 40% increase (2/5 × 100). Be careful with this distinction when reading news about interest rates or polls.
How do I calculate cumulative percentage change?
Multiply the factors together. A 10% increase followed by 20% increase isn't 30%— it's 1.10 × 1.20 = 1.32, or a 32% total increase. For decreases, use decimals less than 1 (a 10% decrease = 0.90).