How to Calculate Percentage Decrease

A percentage decrease measures how much a value has fallen, expressed as a percentage of where it started. Like an increase, it is always measured against the original value. You might use it for a price cut, a fall in sales, a drop in costs, or depreciation.

Percentage Decrease = ((Original Value − New Value) ÷ Original Value) × 100

Three steps:

• Subtract the new value from the original value to find the amount of the decrease.
• Divide that decrease by the original value so it is measured against the starting point.
• Multiply by 100 to turn the fraction into a percentage. The result is positive for a fall.

Notice the order of the subtraction is reversed compared with percentage increase — you take the new value away from the original so the result comes out positive.

To reduce a number by a percentage, turn the percentage into a multiplier by subtracting it from 1:

New Value = Original Value × (1 − Percentage ÷ 100)

This is the same maths as a discount — a 20% decrease in price is a 20% discount. For sale prices in pounds and pence, use the discount calculator or the percent off calculator.

No — a value cannot fall by more than 100% of itself and stay positive. A drop to zero is a 100% decrease. If your result comes out over 100%, you have probably entered the original and new values the wrong way round. (An increase, by contrast, can exceed 100% — see our percentage increase guide.)

Percentage decrease is for values that have gone down. Percentage change covers both directions in one figure — read more in our percentage change guide. A discount is a percentage decrease applied to a price.

Enter your two values into the percentage decrease calculator to see the result, the amount of the decrease and the full working instantly.