Percentage Decrease Calculator
Enter the original and new values to find the percentage decrease between them.
Percentage decrease is how much a value dropped, relative to where it started. Subtract the new value from the original, divide by the original, and multiply by 100. If the result is negative, the value actually increased. The original value is always the denominator.
How to Use This Calculator
Enter the original value and the new, lower value. The calculator returns the percentage decrease and the actual amount of the drop. If you enter a new value that is higher, it reports a negative decrease, meaning the value rose instead.
Percentage decrease is used everywhere from price cuts and discounts to falling measurements, and it always compares the change against the starting point.
How the Calculation Works
The drop is the original minus the new value. Dividing that drop by the original expresses it as a proportion of where you started, and multiplying by 100 turns it into a percentage.
The key rule is that the original value is always the denominator. Dividing by the new value instead is the most common mistake and gives a different, incorrect figure.
percentage decrease = (original − new) ÷ original × 100
Worked Example
A price falls from 80 to 60. The drop is 80 − 60 = 20. Divide by the original: 20 ÷ 80 = 0.25, then multiply by 100 for a 25% decrease.
Note it is not a 33% decrease — that would be dividing by the new value of 60. The starting value, 80, is the correct denominator.
Assumptions and Limitations
- The original value is the denominator and cannot be zero
- A negative result means the value increased, not decreased
- Measures relative change; check the absolute drop too for context
- Results are rounded for display
Who Uses a Percentage Decrease Calculator
Shoppers, analysts, and students use this to find the percentage decrease between two values. Use it to measure a price drop or discount, a fall in sales or weight, or any before-and-after change. Enter the original and new values to get the percentage decline and the amount of the change.
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Open calculator →Frequently Asked Questions
How do you calculate percentage decrease?
Subtract the new value from the original, divide by the original, and multiply by 100. A drop from 80 to 60 is (80 − 60) ÷ 80 × 100 = 25%.
Why divide by the original and not the new value?
Because percentage decrease measures the drop relative to where it started. The original is the reference point, so it is always the denominator. Dividing by the new value gives a different, incorrect number.
What if the value went up?
Then the formula gives a negative percentage, which signals an increase rather than a decrease. For increases, use a percentage increase or percentage change calculation.
Is a 25% decrease the same as a 25% increase back?
No. Going from 80 to 60 is a 25% decrease, but going from 60 back to 80 is a 33.3% increase, because the base value is different in each direction.
How do I find the amount of the decrease?
Simply subtract the new value from the original. From 80 to 60, the amount of decrease is 20, which is the 25% expressed as an actual quantity.
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