How to Calculate Percentage Decrease
A practical guide to calculating percentage decrease with examples, formula breakdowns, and common pitfalls.
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What percentage decrease means
Percentage decrease measures how much a value has gone down compared with its original level. It is common in pricing, inventory, usage, and performance reporting.
Formula
Use this formula:
- ((original value - new value) / original value) × 100
Example
If a value drops from 120 to 100, the decrease is 20. Divide 20 by 120 and multiply by 100 to get 16.67%.
If the new value ends up higher than the original value, the same numbers describe an increase instead.
When to use a calculator
A calculator is useful when you need an exact answer quickly or when the numbers include decimals or negative values.
FAQ
Can percentage decrease be negative?
If the new value is higher than the original value, the formula produces a negative result, which indicates an increase instead.
Why can't the original value be zero?
Because you cannot divide by zero in the percentage change formula.
