Formula
% decrease = (original − new) ÷ |original| × 100New value = value × (1 − % ÷ 100)
- original — the starting value (must not be zero)
- new — the value after the fall
Divide the amount lost by the original value, then multiply by 100.
Worked examples
From 80 to 60
- What do you want to do?
- Find the % decrease between two values
- Original value
- 80
- New value
- 60
Percentage decrease
25%
Amount of decrease: 20
Reduce 200 by 15%
- What do you want to do?
- Decrease a number by a percentage
- Number
- 200
- Decrease by
- 15 %
New value
170
Amount taken off: 30
Multiplier: 0.85
How it works
From 80 down to 60 is a fall of 20. Divided by the original 80 that is 0.25, so the decrease is 25%. Note that climbing back from 60 to 80 is a 33.3% increase, not 25% — each percentage is relative to its own starting point.
To take a percentage off a number, multiply by 1 minus the percentage as a decimal: reducing 200 by 15% gives 200 × 0.85 = 170. For shop prices, including two discounts in a row, use the Discount Calculator.
If the second value is higher the tool tells you it is an increase and points you to the Percentage Increase Calculator.
Assumptions and limits
- An original value of zero is rejected because the percentage would be undefined.
- Decreasing by more than 100% is allowed and produces a negative number, with a note.
Related tools
Percentage Increase CalculatorFind the percentage increase between two values, or add a percentage to a number.Percentage Change CalculatorSigned percentage change from a starting value to a new value, up or down.Percentage Difference CalculatorHow different two values are, as a percentage of their average — order doesn't matter.Discount CalculatorSale price after one or two discounts and tax, or the discount percentage from two prices.Percentage CalculatorFind X% of a number, what percent one number is of another, or the whole from a part.Profit and Loss CalculatorProfit or loss and its percentage from cost and selling price, or find either price.