Percentage increase vs percentage decrease: the practical difference
A practical guide to percentage increase and percentage decrease, common mistakes, price comparisons and how to avoid wrong results.
Increase and decrease move prices in opposite directions
Percentage increase adds a percentage on top of the original value, so the final price goes up. This is the rule you use for markups, growth, added fees and any case where the new value is higher than the starting one.
Percentage decrease removes a percentage from the original value, so the final price goes down. Use it for discounts, sales and price cuts when you want to know what remains after the reduction.
The most common mistakes happen in price comparisons
A frequent error is mixing up the starting value and the final value. Another common mistake is applying the same percentage to two different bases and expecting the same result, which is not true when you compare a discount with a later increase.
For prices, the order also matters. A 20 percent decrease followed by a 20 percent increase does not bring you back to the exact original price, so a percentage calculator is useful when you need the real amount, not just the percentage headline.