A percentage calculator converts between raw numbers and percentages in one step. Find what percent one value is of another, compute X% of Y for discounts, tips and taxes, or measure percent change between an old value and a new one. Every result displays the formula used, so the math is always transparent.
Calculate
How do I calculate X percent of Y?
Multiply Y by X and divide by 100. For example, 20% of 150 is (20 / 100) x 150 = 30. This is the formula behind most discount, tip and tax calculations, and this page runs it for you instantly.
Common uses include sale prices (30% off $80), tips (18% of a $45 bill) and taxes (6% of a purchase). Enter any two numbers above to get the answer with the formula shown.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 is what percent of 150? (30 / 150) x 100 = 20%. This tells you the share one value represents of a total.
Use it for test scores (42 correct out of 50 = 84%), budget shares, or conversion rates. If the result is over 100%, the part is larger than the whole.
How is percent change calculated?
Subtract the old value from the new value, divide by the old value, and multiply by 100. Going from 80 to 100 is ((100 - 80) / 80) x 100 = a 25% increase.
A positive result is an increase and a negative result is a decrease. Percent change is undefined when the old value is zero, since you cannot divide by zero.
What is the difference between percent and percentage points?
A percent is a relative change; a percentage point is an absolute difference between two percents. Rising from 20% to 25% is a 5 percentage point rise but a 25% relative increase.
Mixing these up is a classic error in news and finance reporting. This calculator reports relative percent change, which is the standard meaning of "increased by X%".
Frequently asked questions
What is the formula for percentage?
The three core formulas are: X% of Y = (X/100) x Y; X is what % of Y = (X/Y) x 100; percent change = ((new - old)/old) x 100. Every result on this page shows which formula was used.
How do I calculate a percent increase?
Use the percent-change mode above, or by hand: subtract the old value from the new value, divide by the old value, and multiply by 100. A move from 80 to 100 is a 25% increase.
How do I calculate a percent decrease?
Same formula: ((new - old)/old) x 100 gives a negative number for decreases. From 100 down to 80 is -20%, i.e. a 20% decrease.
Can a percentage be more than 100%?
Yes. "X is what % of Y" exceeds 100% when X is bigger than Y (200 is 200% of 100), and percent change exceeds 100% when a value more than doubles.
Is my data sent anywhere when I use this calculator?
No. All three modes run entirely in your browser with JavaScript. Nothing you type is uploaded or stored.