Discounts, weight loss, falling prices and shrinking budgets are all described as percentage decreases. The percentage tells you the size of the fall relative to where you started, which makes changes of different sizes comparable.
How to use the Percentage Decrease Calculator
- Initial value
- Final value
- Every result field is editable: type into Percentage decrease and Final value plus every other field update to match.
Results update as you type, and everything is calculated in your browser.
How it works
Subtract the final value from the initial value, divide by the initial value and multiply by 100. A negative result means the value actually increased.
Inputs explained
| Field | What to enter |
|---|---|
| Initial value | A number |
| Final value | A number |
What each result means
- Percentage decrease = ([Initial value] – [Final value])÷abs([Initial value])×100
- Difference (final − initial) = [Final value] – [Initial value]
- Final as % of initial = [Final value]÷[Initial value]×100
Example values
How the main result changes when Final value changes and everything else stays at the example values above:
| Final value | Percentage decrease (%) |
|---|---|
| 90 | 64 |
| 135 | 46 |
| 180 | 28 |
| 225 | 10 |
| 270 | -8 |
| 360 | -44 |
Formula
Percentage decrease = (initial − final) ÷ |initial| × 100
Difference = final − initial
Worked example
Inputs: Initial value: 250; Final value: 180.
Results: Percentage decrease = 28 %; Difference (final − initial) = -70; Final as % of initial = 72 %.
Key terms
- Percentage decrease
- The fall in a value as a percentage of its starting value.
Frequently asked questions
How do I calculate a percentage decrease?
(initial − final) ÷ initial × 100. From 250 to 180 that is 70 ÷ 250 × 100 = 28%.
What is the final value after a 28% decrease?
Multiply by (1 − 0.28): 250 × 0.72 = 180. Type 28 into the result to find it.
Is a 100% decrease possible?
Yes, it means the value fell to zero. A decrease of more than 100% means the value became negative.
How do I undo a percentage decrease?
Divide by (1 − p/100). Increasing by the same percentage is not enough.