How do I add or subtract a percentage?

To add a percentage: multiply the original by (1 + percentage/100). To subtract: multiply by (1 - percentage/100). For example, adding 20% to 50: 50 × 1.20 = 60. Subtracting 20% from 50: 50 × 0.80 = 40.

Percentage Calculator — X% of Y, % Change, X is What % of Y

Percentage

Calculation Type

Percentage

of what number?

From (original value)

To (new value)

Part

is what % of total

Results

Pick a calculation type and enter your numbers above.

Three Ways to Calculate a Percentage

The word "percentage" covers at least three different questions that people mean when they reach for a calculator. This tool handles all three.

What is X% of Y?

The most common use case: you want to know the dollar amount of a 15% tip on a $60 bill, or the sale price after a 30% discount, or how much VAT to add at 20%. Formula: (X ÷ 100) × Y.

What is the Percentage Change?

Used to compare two values over time: revenue this quarter vs. last quarter, your weight now vs. six months ago, or a stock price movement. Formula: ((new − old) ÷ |old|) × 100. A positive result means an increase; negative means a decrease.

X is What Percentage of Y?

Used to express a part as a fraction of a whole: if 45 out of 180 students passed, what percentage passed? Formula: (X ÷ Y) × 100. In this example: (45 ÷ 180) × 100 = 25%.

Common Percentage Shortcuts

To find 10%: move the decimal one place left (10% of 340 = 34).
To find 5%: find 10% then halve it (5% of 340 = 17).
To find 1%: move the decimal two places left (1% of 340 = 3.4).
To add a percentage: multiply by 1 + (% ÷ 100). Adding 20% to 80: 80 × 1.20 = 96.

Frequently Asked Questions

Multiply the number by the percentage divided by 100. For example, 15% of 80 = 80 × 0.15 = 12.

Percentage change = ((new value − old value) ÷ |old value|) × 100. A positive result is an increase; negative is a decrease.

Divide X by Y and multiply by 100. For example: 25 is what percent of 200? 25 ÷ 200 × 100 = 12.5%.

To add: multiply by (1 + percentage/100). To subtract: multiply by (1 − percentage/100). Adding 20% to 50: 50 × 1.20 = 60. Subtracting 20% from 50: 50 × 0.80 = 40.

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