Percentage Decrease Calculator
Subtract a percentage from a number and see the reduction and final value.
What the Percentage Decrease Calculator does
Decreasing a number by a percentage multiplies it by (1 − rate). It is the arithmetic behind discounts, depreciation, budget cuts and price drops.
Formula
New value = Old × (1 − Rate ÷ 100)Decrease = Old × Rate ÷ 100
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Starting value | number | Yes | — |
| Decrease by | % | Yes | — |
How to use it
- Enter Starting value and Decrease by.
- Select Calculate.
Worked example
A $1,200 laptop is cut by 25%.
- Starting value
- 1200
- Decrease by
- 25
1,200 × 0.75 = $900, a reduction of $300.
Reading the result
- A decrease multiplies by (1 − rate), so 20% off is a factor of 0.8.
- A decrease can never exceed 100%, since that would take the value below zero.
Common mistakes
- Adding successive discounts together. Two 20% reductions compound to ×0.64, a 36% total cut rather than 40%.
- Undoing a decrease by adding the same percentage back. Reversing 20% off means dividing by 0.8, which is a 25% increase.
Frequently asked questions
Do two 20% discounts equal 40% off?
No. Two successive 20% cuts leave 0.8 × 0.8 = 0.64 of the price, which is 36% off, not 40%.