Percentage Decrease Calculator
Instantly calculate the percentage decrease between two values. Enter the original and new values to find the percentage decrease, the difference amount, and the new value — with step-by-step working shown.
Percentage Decrease Calculator
Enter the original and new values to calculate
The original or starting value before the decrease
The new or final value after the decrease
Your Result
Percentage decrease breakdown
Enter the original and new values, then click Calculate to see the percentage decrease with step-by-step working.
Common Percentage Decreases
Quick reference showing what common percentage decreases look like when applied to a starting value of 100.
| Percentage Decrease | Decrease Amount | New Value | Multiplier |
|---|---|---|---|
| 5% | 5 | 95 | × 0.95 |
| 10% | 10 | 90 | × 0.90 |
| 15% | 15 | 85 | × 0.85 |
| 20% | 20 | 80 | × 0.80 |
| 25% | 25 | 75 | × 0.75 |
| 30% | 30 | 70 | × 0.70 |
| 40% | 40 | 60 | × 0.60 |
| 50% | 50 | 50 | × 0.50 |
| 60% | 60 | 40 | × 0.40 |
| 75% | 75 | 25 | × 0.25 |
| 80% | 80 | 20 | × 0.20 |
| 90% | 90 | 10 | × 0.10 |
Percentage Decrease FAQ
Everything you need to know about calculating percentage decrease, with examples and formulas.
To calculate percentage decrease, use the formula: Percentage Decrease = ((Original Value − New Value) ÷ Original Value) × 100. For example, if a product was £80 and is now £60, the decrease is £20. The percentage decrease is (20 ÷ 80) × 100 = 25%. This means the price has decreased by 25%.
The formula for percentage decrease is: % Decrease = ((Original − New) ÷ Original) × 100. Alternatively, if you know the percentage decrease and want to find the new value: New Value = Original × (1 − percentage/100). For example, a 20% decrease on £100 gives: £100 × (1 − 0.20) = £80.
Percentage decrease measures how much a value has reduced from its original amount, while percentage increase measures how much a value has grown. The formulas are similar: Decrease = ((Original − New) ÷ Original) × 100, and Increase = ((New − Original) ÷ Original) × 100. The key difference is which value is subtracted from which — if the new value is smaller, it’s a decrease; if larger, it’s an increase.
To calculate a 20% decrease, multiply the original value by 0.80 (which is 1 − 0.20). For example, a 20% decrease on £150 is: £150 × 0.80 = £120. The decrease amount is £150 − £120 = £30. You can also calculate it as: £150 × 20 ÷ 100 = £30 decrease, so the new value is £150 − £30 = £120.
No, percentage decrease cannot be more than 100% when going from a positive value to another positive value, because that would mean the new value is negative. A 100% decrease means the value has gone to zero. However, if the new value is negative (e.g., going from 50 to −10), the ‘decrease’ would be 120%, which represents a change of direction rather than a simple decrease.
To reverse a percentage decrease and find the original value, use the formula: Original = New Value ÷ (1 − percentage/100). For example, if a price after a 25% decrease is £75, the original price was: £75 ÷ (1 − 0.25) = £75 ÷ 0.75 = £100. Note that you cannot simply add the percentage back — a 25% decrease followed by a 25% increase does not return to the original value.
Common real-life examples of percentage decrease include: sale discounts (e.g., 30% off a £100 item = £70), price reductions in shops, depreciation of assets like cars (which lose around 15-20% of value per year), population decline, weight loss (e.g., losing 10% of body weight), and reductions in measurements like temperature or pressure.
Yes, a 50% decrease is exactly the same as halving the original value. If something decreases by 50%, the new value is half of the original. For example, a 50% decrease on £200 gives £100, which is exactly half. Similarly, a 25% decrease leaves 75% (three-quarters), and a 75% decrease leaves 25% (one-quarter).