Skip to content
NumberCalculator365

Percentage Calculator

Calculate a percentage of an amount, express one number as a percentage of another, or measure percentage change. Switch modes to match the question rather than rearranging a formula yourself.

Percentage Calculator tool

About the Percentage Calculator

Use this tool to check a sale discount, compare a score with its total, or describe growth and decline. Each result includes the calculation so students, shoppers, and anyone checking a report can follow the arithmetic.

How Is Percentage Calculated?

Percent means per hundred. Divide a percentage by 100 before multiplying it by an amount.

For percentage change, the original value is the reference. This calculator uses its absolute magnitude for negative starting values, so an increase in numerical value remains an increase.

X% of Y = (X ÷ 100) × Y
X as a percentage of Y = (X ÷ Y) × 100
Percentage change = ((Y − X) ÷ |X|) × 100

Example

15% of 200 = 0.15 × 200 = 30.

How to Use the Percentage Calculator

  1. Choose percentage of an amount, percentage of a total, or percentage change.
  2. Enter X as the percentage, part, or original value for the selected mode.
  3. Enter Y as the amount, total, or new value.
  4. Read the live result and check its formula.
  5. For change mode, review the increase or decrease label and the absolute change.

Percentage Calculator Examples

Find a portion

18% of 250 = 45.

Compare a part

45 out of 180 is 45 ÷ 180 × 100 = 25%.

Measure a decline

A change from 80 to 60 is (60 − 80) ÷ 80 × 100 = −25%, a 25% decrease.

Reverse percentages

If a final amount is known after a 20% discount, divide it by 0.80 to recover the original. Subtracting 20% from the final amount does not reverse the discount.

Successive changes

Percentage changes multiply rather than simply cancel. Increasing 100 by 20% gives 120; reducing 120 by 20% gives 96.

Frequently Asked Questions

What happens when Y is zero?

In percentage-of mode, any finite percentage of zero is zero. In ratio mode, division by a zero total is undefined. In change mode, a zero new value is valid if the original value is nonzero.

Can percentage change start at zero?

No. A zero original value makes the relative change undefined; report the absolute change instead.

Can the result exceed 100%?

Yes. For example, 150 is 150% of 100, and doubling a value is a 100% increase.

Are percentage points the same as percent change?

No. A rate rising from 20% to 25% rises by 5 percentage points but by 25% relative to its original rate.

How are negative starting values treated?

The denominator is the absolute original value. From −100 to −50, the numerical increase is 50%, using 100 as the reference magnitude.

Related Calculators

Discount Calculator

Sale price and savings from a percent off or dollar discount.

Tip Calculator

Tip amount and per-person split for any bill.

Fraction Calculator

Add, subtract, multiply and divide fractions and mixed numbers.

Average Calculator

Mean, median, mode and range of any list of numbers.

Grade Calculator

Weighted course grade and the score needed on your final.