How do I calculate percentage increase?

Subtract the original value from the new value, divide by the original value, then multiply by 100. Example: (100 - 80) / 80 × 100 = 25% increase.

How do I calculate percentage decrease?

The formula is the same: (new - original) / original × 100. If the result is negative, you have a decrease. Example: (70 - 80) / 80 × 100 = -12.5%.

Percentage Increase and Decrease Calculator

Calculate the percentage increase or decrease between two values, or find the new value after applying a percentage change.

By AbraCalc Editorial Team · Reviewed by AbraCalc Methodology Review · Last reviewed: 2026-06-25 2 sources

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Cite this tool

APA

AbraCalc. (2026). Percentage Increase and Decrease Calculator [Online calculator]. Retrieved from https://abracalc.com/calculator/percentage-increase-decrease/

BibTeX

@misc{abracalc-percentage-increase-decrease, author = {AbraCalc}, title = {Percentage Increase and Decrease Calculator}, year = {2026}, howpublished = {\url{https://abracalc.com/calculator/percentage-increase-decrease/}} }

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How to use this tool

Enter the original (starting) value.
Enter the new value.
Read the percentage change and absolute difference.
A negative percentage indicates a decrease.

Calculate the percentage change between any two numbers — useful for prices, grades, salaries, and more.

Formula

Percentage Change = ((New Value − Original Value) ÷ Original Value) × 100

If the result is positive the change is an Increase; if negative, a Decrease; if zero, No change.

How it works

This calculator computes the relative change between two values by dividing the absolute difference by the original value and expressing the result as a percentage. It simultaneously reports the raw numerical difference and labels the direction of change. The formula requires a non-zero original value; entering zero as the original will produce undefined results.

Worked example

Original value = 80; New value = 100.
Absolute difference = 100 − 80 = 20.
Percentage change = (20 ÷ 80) × 100 = 25%.
Since the difference is positive, the direction is Increase.

Percentage change: 25% Increase | Absolute difference: 20

Common mistakes to avoid

Swapping the original and new values -- using the new value as the denominator inflates percentage change when prices rise and deflates it when they fall.
Confusing percentage points with percent change: a rate rising from 2% to 3% is a 1 percentage-point increase but a 50% relative increase.
Treating a symmetric reversal as equal -- a 50% decrease followed by a 50% increase does not return to the original value; the second base is smaller.

Key terms

Percentage change: The relative difference between two values expressed as a percentage of the original value.
Absolute difference: The raw numerical gap between the new and original values, without reference to the original size.
Original value: The starting or reference value against which the change is measured — the denominator in the percentage change formula.
Percentage increase: A positive percentage change, meaning the new value is greater than the original.
Percentage decrease: A negative percentage change, meaning the new value is less than the original.

Frequently asked questions

How do I calculate percentage increase?: Subtract the original value from the new value, divide by the original value, then multiply by 100. Example: (100 - 80) / 80 × 100 = 25% increase.
How do I calculate percentage decrease?: The formula is the same: (new - original) / original × 100. If the result is negative, you have a decrease. Example: (70 - 80) / 80 × 100 = -12.5%.