Percentage Decrease Calculator
Calculate a value after a percentage decrease, or find what percentage decrease goes from one value to another. Two-way calculation with formula
How to Calculate Percentage Decrease
Formula: ((Original - New) / Original) × 100. So if a price drops from £80 to £60, the decrease is ((80-60)/80) × 100 = 25%. The result is always positive (representing the magnitude of decrease); the direction is implied by 'decrease'.
Used for sales discounts, weight loss, profit margins shrinking, market downturns. A 25% decrease in stock value from £40 to £30 = same as a 'sale' of 25% off £40. Important: percentage decreases don't compound the same way as increases - a 50% decrease followed by a 50% increase doesn't return to original (£100 → £50 → £75, not £100).
Common Percentage Decreases
| From | To | % Decrease |
|---|---|---|
| 100 | 90 | 10% |
| 100 | 75 | 25% |
| 100 | 50 | 50% |
| 100 | 25 | 75% |
| 80 | 60 | 25% |
| 60 | 45 | 25% |
| £200 | £170 | 15% |
| £500 | £350 | 30% |
Frequently Asked Questions
Why doesn't 50% decrease then 50% increase return to original?
Math: £100 - 50% = £50. £50 + 50% = £75. The base changed - the second percentage applies to £50, not £100. To return to £100 from £50, you need a 100% increase. This 'percentage of what?' issue causes lots of confusion in finance discussions.
Can decrease be more than 100%?
No - a 100% decrease leaves you with zero. You can't decrease below zero with percentages. If something drops from £100 to -£50, the formula technically gives 150% decrease, but this rarely appears in practice. Typical decreases stop at 100% (the value reaches zero).
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