Percentage Decrease Calculator
Calculate the percentage decrease from one value to a lower value, or find the new value after applying a given percentage decrease to a starting value. Formula: percentage decrease = ((original − new) ÷ original) × 100.
What is the percentage decrease?
Original value + new (lower) value → percentage decrease
Enter the original value and the new (lower) value.
Related: Percentage Increase · Percentage Calculator
What is the new value?
Original value + % decrease → new value
Enter the starting value and the percentage decrease to apply.
How the Percentage Decrease Calculator works
This calculator has two modes. The first works out the percentage decrease between an original value and a lower new value — useful for measuring price drops, salary reductions, or falling statistics. The second applies a known percentage decrease to a starting value to calculate the resulting lower figure, which is helpful when modelling scenarios such as budget cuts or depreciation.
Percentage decreases are commonly encountered in UK finance when assessing sale discounts, falling property values, declining interest rates, or reductions in benefit payments. Being able to verify the quoted percentage — or calculate its pound value — helps you make informed decisions and catch errors in published figures.
A frequent error is trying to reverse a percentage decrease by adding the same percentage back. This does not restore the original value. For instance, a 20% decrease on £250 gives £200, but adding 20% back to £200 gives £240, not £250. To correctly reverse a percentage decrease and recover the original, divide the reduced value by (1 minus the percentage as a decimal).
Frequently asked questions
How do I calculate a percentage decrease?
To calculate a percentage decrease, subtract the new (lower) value from the original value to find the absolute decrease, then divide by the original value and multiply by 100. Formula: ((original − new) ÷ original) × 100. For example, if a price fell from £250 to £200, the decrease is £50. £50 ÷ £250 × 100 = 20% decrease.
What is the difference between percentage decrease and percentage change?
Percentage decrease is a specific case of percentage change where the new value is lower than the original. Percentage change covers both increases and decreases: a positive result means an increase, a negative result means a decrease. The formula is the same in both cases: ((new − original) ÷ original) × 100. A result of −20% represents a 20% decrease.
How do I find the original price after a percentage decrease?
To find the original value after a percentage decrease, divide the new value by (1 minus the percentage decrease expressed as a decimal). For example, if a price fell by 20% to reach £200: £200 ÷ (1 − 0.20) = £200 ÷ 0.80 = £250. This is useful for working out the pre-sale price of a discounted item when you know the percentage off.
Can a percentage decrease exceed 100%?
A standard percentage decrease cannot exceed 100%, because a 100% decrease means the value has reached zero — there is nothing left to decrease further. In everyday contexts such as prices or quantities, values cannot go below zero, so percentage decreases are bounded between 0% and 100%. However, in contexts where values can go negative — such as temperature, profit and loss, or certain financial instruments — the concept of a 'decrease' beyond 100% can be meaningful in practice.