Percentage Decrease Calculator
Calculate how much a value has decreased as a percentage. Enter the original value and the new (lower) value to find the percentage decrease.
Decrease a Number by Percentage
Calculate the result when you decrease a number by a certain percentage. Useful for discounts, pay cuts, and reductions.
Find Original Value Before Decrease
Know the current value and the percentage it was decreased by? Calculate the original value before the decrease.
Percentage decrease measures how much a value has dropped compared to its original amount. Whether you are tracking weight loss, calculating price reductions, or measuring declining sales, this calculator shows you the exact percentage decrease with step-by-step working.
For increases, use our percentage increase calculator. For comparing two values without a before/after relationship, try the percentage difference calculator.
Percentage Decrease Formula
The percentage decrease formula compares how much a value has dropped relative to the original:
In simple terms: find the decrease, divide by the original, multiply by 100.
The price decreased by 25%
How to Decrease a Number by a Percentage
To reduce a number by a percentage, use this formula:
$500 decreased by 20% equals $400
To decrease by 10%, multiply by 0.90. For 20%, multiply by 0.80. For 25%, multiply by 0.75. For 50%, multiply by 0.50. The multiplier is always (100 – decrease%) / 100.
How to Find the Original Value Before a Decrease
If you know the current value and the percentage it was decreased by, you can find the original:
The original price was $100
Common Mistake: Percentage Up Then Down
A 25% increase followed by a 25% decrease does NOT return to the original value. This catches many people out!
You end up with $93.75, not $100. The percentages are calculated from different bases.
This happens because the 25% increase is calculated on $100, but the 25% decrease is calculated on $125 (a larger number). To return to $100 from $125, you would need a 20% decrease, not 25%.
Percentage Decrease Examples
Example 1: Weight Loss
You lost 10% of your body weight
Example 2: Sales Decline
Sales decreased by 16%
Example 3: Budget Cut
New budget is $102,000
Example 4: Finding Original Price
Original price was $80
Common Percentage Decreases
| Decrease | Multiplier | $100 Becomes |
|---|---|---|
| 5% | 0.95 | $95 |
| 10% | 0.90 | $90 |
| 15% | 0.85 | $85 |
| 20% | 0.80 | $80 |
| 25% | 0.75 | $75 |
| 30% | 0.70 | $70 |
| 33.33% | 0.6667 | $66.67 |
| 50% | 0.50 | $50 |
| 75% | 0.25 | $25 |
Frequently Asked Questions
Subtract the new value from the original value to find the decrease. Divide the decrease by the original value. Multiply by 100. Formula: ((Original – New) / Original) x 100.
The percentage decrease is 25%. Calculation: (100 – 75) / 100 x 100 = 25%.
Multiply the number by 0.80 (which is 1 – 0.20). For example, $150 decreased by 20% = $150 x 0.80 = $120.
Because the percentages are calculated from different bases. The increase is on the original, but the decrease is on the larger increased value. A 20% increase followed by a 20% decrease results in 96% of the original.
Divide the sale price by (1 – discount/100). For a 30% discount with sale price of $70: Original = $70 / 0.70 = $100.
Percentage decrease uses the original value as the base and measures decline over time. Percentage difference uses the average of both values as the base and compares two values without implying one came first.
Not in the usual sense. A 100% decrease means the value went to zero. However, if comparing to a negative value or in certain contexts with losses exceeding initial value, you might see figures over 100%.
Use the same formula: ((Last Year – This Year) / Last Year) x 100. For example, revenue dropped from $500,000 to $450,000: ($50,000 / $500,000) x 100 = 10% year-over-year decrease.
Related Calculators
Back to Percentage Calculator for more calculation tools.