Percentage Calculator
Percent of a number, reverse percentages, and percent change — the three percentage questions everyone hits, answered instantly with the formula shown.
How to use this tool
- Pick the question you're answering: percent of a number, what percent one number is of another, or percent change.
- Fill in the two numbers — the answer and the formula used appear instantly.
How it works
Percent of: X% of Y = Y × (X ÷ 100). What percent: X ÷ Y × 100. Percent change: (new − old) ÷ old × 100 — note the divisor is the original value, which is why a 50% loss needs a 100% gain to recover.
Tip for mental math: X% of Y always equals Y% of X. 4% of 75 feels hard; 75% of 4 is obviously 3.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percent divided by 100. 15% of 80 = 80 × 0.15 = 12.
How do I work out a percent increase or decrease?
Subtract the original from the new value, divide by the original, and multiply by 100. From 80 to 92: (92 − 80) ÷ 80 × 100 = 15% increase.
What's the difference between percent change and percentage points?
Going from 10% to 15% is a rise of 5 percentage points, but a 50% relative increase. News and statistics often mix these up — this calculator computes the relative change.