How do you calculate a percentage decrease?

New value = original × (1 − percent/100). 100 decreased by 15% = 85. Savings = original − new value.

Percentage Decrease Calculator

Decrease a starting value by any percentage. Useful for discounts, reductions, depreciation estimates, and “minus X%” math.

Understanding percentage decrease

A percentage decrease lowers a starting value by a stated percent. It is the natural language for discounts, reductions, and “take X% off.”

Good for

Taking a clean percent off a list price or quantity
Modeling a reduction target (“cut usage 12%”)
Explaining why 20% off twice is not 40% off

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Percentage Increase / Decrease

Increase or decrease a value by a percentage

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By percentage

Direction

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Result

Enter values to calculate

Decrease a starting value by any percentage. Useful for discounts, reductions, depreciation estimates, and “minus X%” math. Read related guides.

Formula

New value = original × (1 − percent/100). Decreasing 100 by 15% multiplies by 0.85 and yields 85. Savings (the amount removed) = original × (percent/100).

After a decrease, the remaining share is (100 − percent)%. A 30% decrease leaves 70% of the original.

Discounts and markdowns

Retail “% off” is a percentage decrease on price. For coupons stacked one after another, apply each decrease to the current price; do not add the percents. Our discount calculator focuses on sale price and savings labels for shopping scenarios.

Depreciation rules in accounting can be more complex than a single percent decrease; this tool is for straightforward percent-off arithmetic.

Compare with percentage change

If you already know the before and after numbers and want the rate, use percentage change. This page assumes you know the before value and the percent to remove.

Worked examples

Example calculations for Percentage Decrease
Question	Answer
100 decreased by 15%	85
200 decreased by 10%	180
80 decreased by 25%	60

Formula reference

Goal	Formula
Value after decrease	value × (1 − percent/100)

FAQ — Percentage Decrease

How do you calculate a percentage decrease?: New value = original × (1 − percent/100). 100 decreased by 15% = 85. Savings = original − new value.

Educational tool only — not tax, legal, or financial advice. Contact us with corrections.

Free calculators for every common percentage problem.