Multiply Y by X and divide by 100. For example, 15% of 200 = 200 × 15 ÷ 100 = 30.

How do I find what percent X is of Y?

Divide X by Y, then multiply by 100. For example, 30 out of 200 = (30 ÷ 200) × 100 = 15%.

How is percentage change calculated?

Subtract the old value from the new value, divide by the old value, then multiply by 100. A positive result is an increase; a negative result is a decrease.

What is the difference between percentage and percentage points?

A percentage expresses a fraction of a whole (e.g. 40%). A percentage point is the arithmetic difference between two percentages — going from 30% to 40% is a 10 percentage-point increase but a 33.3% relative increase.

Can I calculate a negative percentage change?

Yes. If the new value is smaller than the old value the result will be negative, indicating a decrease. For example, going from 80 to 60 is a −25% change.

How do I find the whole when I know the part and the percent?

Divide the part by the percent written as a decimal. If 30 is 15% of a number, the number is 30 ÷ 0.15 = 200. In the Of what? tab, enter 30 as the part and 15 as the percent. You can check the answer in the X% of Y tab: 15% of 200 = 30.

How do I add or subtract a percentage from a number?

Multiply by 1 plus or minus the percent as a decimal. 200 plus 15% is 200 × 1.15 = 230, and 200 minus 15% is 200 × 0.85 = 170. In the ± % tab, enter 200, pick Add or Subtract, and enter 15. The two steps do not cancel out: 170 plus 15% is 195.5, not 200.

Is percent change the same as percent difference?

No. Percent change divides by the starting value, so direction matters: 50 to 75 is +50%, but 75 to 50 is −33.33%. Percent difference compares two values with no start or end and divides the gap by their average: 25 ÷ 62.5 × 100 = 40%. The % Change tab gives percent change only.

Percentage Calculator

Instantly calculate what X% of a number is, find what percent one number is of another, find the whole from a part and its percent, compute percentage change between two values, or add or subtract a percentage.

To find X% of Y, multiply Y by X and divide by 100: 15% of 200 = 30.

What is X% of Y?

Percentage (X)

Number (Y)

Enter values on the left to see the result

X% of Y

Result = Y × X ÷ 100

X of Y %

Result = (X ÷ Y) × 100

% Change

Result = ((New − Old) ÷ Old) × 100

Y ± X%

Result = Y × (1 ± X ÷ 100)

X is Y% of ?

Result = X ÷ Y × 100

Copied!

Quick answer

To find X% of Y, multiply Y by X and divide by 100: 15% of 200 = 30. To find what percent X is of Y, divide X by Y and multiply by 100: 18 out of 24 = 75%. Percent change is (new − old) ÷ old × 100, so going from 80 to 100 is a 25% increase and from 80 to 60 a 25% decrease. To add or subtract a percent, multiply by 1 plus or minus the percent: 200 + 15% = 230 and 200 − 15% = 170.

Examples

Question	Math	Answer
15% of 200	200 × 15 ÷ 100	30
20% of 149	149 × 20 ÷ 100	29.8
18 is ?% of 24	18 ÷ 24 × 100	75%
1 is ?% of 3	1 ÷ 3 × 100	33.3333%
80 to 100	20 ÷ 80 × 100	+25%
200 to 150	−50 ÷ 200 × 100	−25%
200 + 15%	200 × 1.15	230
200 − 15%	200 × 0.85	170
30 is 15% of ?	30 ÷ 15 × 100	200

Pick a tab: X% of Y, X of Y %, % Change, ± % or Of what?

Summary

This percentage calculator covers five common percentage problems in one page. Enter two numbers to find what X% of Y equals, determine what percentage one value is of another, find the whole when you know a part and its percent, calculate the percentage change (increase or decrease) between a start value and an end value, or add a percentage to a number or subtract it. All calculations run instantly in your browser with no data sent to any server.

How it works

Choose one of the five calculation modes using the tab buttons (the ± % tab adds or subtracts a percentage, and Of what? finds the whole from a part and its percent).
Enter the required numbers into the input fields.
The result updates instantly as you type.
Click "Copy Result" to copy the answer to your clipboard.
Use the Reset button to clear all fields and start a new calculation.

Use cases

Find a discount amount — e.g. 20% off a $149 item.
Calculate a tip at a restaurant.
Determine what share of a total budget one category takes.
Track sales growth or decline month-over-month.
Convert a test score (e.g. 18 out of 24) to a percentage.
Compute a commission on a sale.
Check VAT or tax amounts on an invoice.
Measure weight-loss or gain as a percentage of starting weight.

Frequently Asked Questions

Last updated: 2026-06-04 · Reviewed by Nham Vu