Percentage Increase Calculator
Calculate the percentage increase from a starting value to a new value, or apply an increase directly.
How to use this calculator
- Enter the starting (old) value.
- Enter the new value.
- The result is the signed percentage increase; a negative result means the value actually fell.
The formula
Increase % = (New − Old) ÷ Old × 100- New
- The value after the change
- Old
- The starting value (cannot be zero)
How it works
The increase is measured relative to where you started. Going from 80 to 100 is a gain of 20 on a base of 80, which is 20 ÷ 80 = 0.25, or 25%.
To apply a percentage increase to a number, multiply by (1 + percentage/100). A 25% increase on 80 is 80 × 1.25 = 100.
Worked example
Rent rises from $1,200 to $1,290 per month.
- 1Change = 1,290 − 1,200 = 90
- 290 ÷ 1,200 = 0.075
- 30.075 × 100 = 7.5
The rent increased by 7.5%.
When this calculator is useful
- Price and rent changes
- Salary raises
- Growth in savings or traffic
- Year-over-year comparisons
Frequently asked questions
Is a 50% increase followed by a 50% increase equal to 100% overall?
No. Percentages compound: ×1.5 then ×1.5 is ×2.25, a 125% total increase.
How do I reverse a percentage increase?
Divide by (1 + p/100), do not subtract p%. Reversing a 25% increase means dividing by 1.25.