PercentPoint

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Percentage Calculator

A percentage calculator finds how much a value has grown, shrunk, or differs from another value, expressed as a percentage. Percentage increase and decrease measure change relative to a starting, original value, while percentage difference measures the gap between two values relative to their average. Enter any two numbers below to get an instant result along with the exact formula used.

Find percentage increase

Percentage increase

Enter both values above.

Find the increased value

Increased value

Enter a value and a percentage above.

How to calculate percentage increase, decrease, and difference

Percentage increase

Percentage Increase = ((New Value − Original Value) / Original Value) × 100
  1. Subtract the original value from the new value to find the amount of increase.
  2. Divide that increase by the original value.
  3. Multiply the result by 100 to convert it to a percentage.
Worked example: a value rises from 50 to 65. Increase = 65 − 50 = 15. 15 ÷ 50 = 0.3. 0.3 × 100 = 30%. The value increased by 30%.

Percentage decrease

Percentage Decrease = ((Original Value − New Value) / Original Value) × 100
  1. Subtract the new value from the original value to find the amount of decrease.
  2. Divide that decrease by the original value.
  3. Multiply the result by 100 to convert it to a percentage.
Worked example: a value falls from 150 to 120. Decrease = 150 − 120 = 30. 30 ÷ 150 = 0.2. 0.2 × 100 = 20%. The value decreased by 20%.

Percentage difference / percentage change

Percentage change is signed, so it reads directly as an increase or a decrease from a specific original value:

Percentage Change = ((Value 2 − Value 1) / Value 1) × 100

Percentage difference is unsigned. It is used when neither number is clearly the "original," so the calculation compares both values against their average instead of picking one as the base:

Percentage Difference = (|Value 1 − Value 2| / ((Value 1 + Value 2) / 2)) × 100
  1. Find the difference between the two values (subtract one from the other).
  2. For percentage change, divide by Value 1. For percentage difference, divide by the average of both values and drop the sign.
  3. Multiply the result by 100.
Worked example: comparing 40 and 50. Percentage change = (50 − 40) ÷ 40 × 100 = 25% (an increase). Percentage difference = |40 − 50| ÷ ((40 + 50) / 2) × 100 = 10 ÷ 45 × 100 ≈ 22.22%.

Percentage increase vs. decrease vs. difference: which one to use

Use percentage increase or percentage decrease whenever there is a clear starting point, such as last year's revenue versus this year's, or an original price versus a sale price. Use percentage difference when there is no defined original value, such as comparing two competing products' prices or two independent measurements where neither one is the "before" figure.

Metric Has a clear original value? Signed or unsigned? Typical use
Percentage increase Yes Signed (positive) Growth, raises, gains
Percentage decrease Yes Signed (positive, read as a drop) Discounts, losses, decline
Percentage difference No Unsigned Comparing two independent values

Common uses for a percentage calculator

People reach for a percentage calculator for the same handful of everyday questions. Below are the most common ones this tool supports.

Frequently asked questions

What is the formula for percentage increase?

Percentage increase is calculated as ((New Value − Original Value) / Original Value) × 100. The result tells you by what percent the value grew relative to the original amount.

What is the formula for percentage decrease?

Percentage decrease is calculated as ((Original Value − New Value) / Original Value) × 100. The result tells you by what percent the value shrank relative to the original amount.

Is percentage difference the same as percentage change?

No. Percentage change compares a new value to a specific original value, so it is signed and directional. Percentage difference compares two values with no defined starting point, using their average as the base, so it is always unsigned.

How do I calculate a 20% decrease from 150?

Multiply 150 by 20% (0.20) to get 30, then subtract that from 150 to get 120. A 20% decrease from 150 equals 120.

Can percentage increase be more than 100%?

Yes. A percentage increase exceeds 100% whenever the new value is more than double the original value. For example, going from 10 to 25 is a 150% increase.

Why is my percentage change negative?

A negative percentage change means the new value is lower than the original value, which represents a decrease. The negative sign indicates the direction of the change, not an error in the calculation.

What's the difference between percentage points and percentage change?

A percentage point is a simple arithmetic difference between two percentages, such as going from 20% to 25% being a 5 percentage point increase. Percentage change measures that same move as a relative percentage, which in this example is a 25% increase.

What if the original value is zero?

Percentage increase and decrease cannot be calculated when the original value is zero because the formula requires dividing by that value. In this case, use percentage difference instead, since it is based on the average of the two values rather than a single starting point.

Is percentage difference always positive?

Yes. Percentage difference uses the absolute value of the gap between two numbers, so it is always reported as a positive percentage regardless of which value is larger.