Percentage Increase and Decrease Calculator
Calculate the percentage increase or decrease between two values, or find the new value after applying a percentage change.
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
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
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%.