Percentage Calculator

Calculate percentages and percentage changes easily.

Calculation Type

Percentage (%)

Number

Result

25% of 100

Common Percentage Calculations

10% of 100 = 10

25% of 80 = 20

50% of 200 = 100

100% of 150 = 150

Frequently Asked Questions

How do I calculate percentage of a number?

To find X% of Y, multiply Y by X/100. For example, 25% of 80 = 80 × 0.25 = 20.

How do I calculate percentage increase?

To find the percentage increase from A to B: ((B - A) / A) × 100. For example, from 50 to 75: ((75 - 50) / 50) × 100 = 50%.

What percent is X of Y?

To find what percent X is of Y: (X / Y) × 100. For example, what percent is 30 of 150? (30 / 150) × 100 = 20%.

A percentage calculator handles the three small but constant math questions that show up everywhere: what percent X is of Y, what is N percent of X, and what does X become after increasing or decreasing by N percent. These cover most of the daily arithmetic involving percentages, from discounts and tips to tax rates, salary raises, year-over-year growth, and grade scores.

The three modes are quick to describe. In 'X is what percent of Y' mode, the answer is X divided by Y, multiplied by 100. So 45 out of 200 is 22.5 percent. In 'N percent of X' mode, multiply X by N/100, so 15 percent of 80 is 12. In 'X plus/minus N percent' mode, multiply X by (1 + N/100) for an increase or (1 − N/100) for a decrease, so 200 increased by 8 percent becomes 216, and 200 decreased by 8 percent becomes 184. The last mode is the one most calculators get wrong, since the common mistake is to add N percent of X to X in the wrong direction or to apply the change to the wrong base.

Real-world uses are everywhere. A $70 jacket marked '30 percent off' becomes $49, and with a 7 percent sales tax layered on top it becomes about $52.43. A salary that moves from $60,000 to $64,200 is a 7 percent raise. A stock that goes from $48 to $54 is a 12.5 percent gain; the same move in reverse, from $54 down to $48, is an 11.1 percent loss, not a 12.5 percent loss, because the base changed. That asymmetry is the most common source of 'the numbers do not match' confusion in finance and shopping.

Percentages also show up in error margins, statistics, body composition, and screen brightness settings. The same arithmetic powers all of them, which is why a single tool with all three modes is more useful than a string of single-purpose calculators.

How to use

Pick a mode: 'X is what percent of Y', 'N percent of X', or 'X plus/minus N percent'.
Enter the two numbers involved. For discounts and taxes, the base is always the price before the change.
Click calculate to see the result, and check the optional breakdown that shows the multiplication step by step.
Switch modes or change the inputs to chain operations, for example apply a discount, then add tax, to see the final price.

Formula

What percent: (X ÷ Y) × 100. N percent of X: X × N ÷ 100. Increase: X × (1 + N/100). Decrease: X × (1 − N/100). Example: 30% off $70 = 70 × 0.70 = $49, and that amount plus 7% tax = 49 × 1.07 = $52.43.

Interpreting your results

Read the result as a ratio, not as a count. 25 percent of 80 is 20, but 20 percent of 25 is also 5, and 5 percent of 20 is 1, all using the same arithmetic. The output is most useful when paired with the base value and the change, so a percentage gain or loss always has a clear reference point.

Frequently asked questions

Why does a 50 percent increase followed by a 50 percent decrease not return to the original value?

Because the base changes. A 50 percent increase on 100 gives 150, and a 50 percent decrease on 150 gives 75. To return to 100 after a 50 percent increase, the decrease must be 33.3 percent, not 50 percent. This asymmetry is the most common source of percentage confusion.

How do I calculate a tip on a bill?

Pick a tip percentage (15 to 20 percent is the U.S. norm), then multiply the bill by that percentage as a decimal. A $58 bill at 18 percent is 58 × 0.18 = $10.44 tip, with a final total of $68.44. Tip on the pre-tax subtotal when the receipt shows tax separately.

What is the difference between percentage points and percent?

A percentage point is the absolute difference between two percentages. A percent change is a relative difference. A rate that goes from 4 percent to 5 percent has risen by 1 percentage point, but by 25 percent in relative terms. The two are often confused in news headlines, which can make a small change look huge.

Can I use this to figure out a sale price?

Yes. In 'X minus N percent' mode, enter the original price as X and the discount as N. A $120 item at 25 percent off comes out to $90. To add sales tax on top, chain the result through the 'X plus N percent' mode with the local tax rate.