Percentage Decrease Calculator
Measure how much a value has fallen in percent, take a percentage off a number, or find what it was before the drop. Answers appear as you type.
- Instant results
- Step-by-step working
- Excel formula
- No sign-up
Percentage change
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Decrease a number by a percentage
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Original value before a decrease
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How much percent off?
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What is a percentage decrease?
A percentage decrease shows how much a value has fallen relative to its starting point. If your weight goes from 90 kg to 81 kg, it has dropped by 9 kg, or 10% of the starting 90 kg. Percentage decreases describe price cuts, weight loss, falling costs and shrinking numbers in a way that can be compared across different sizes.
How to use Percentage Decrease Calculator
- To measure a drop, enter the starting and ending values in “Percentage change”. A negative result is a decrease.
- To reduce a number, enter it with the percentage in “Decrease a number by a percentage”.
- To reverse a decrease, enter the reduced value and the percentage in “Original value before a decrease”.
- Open “Show working” for the steps and an Excel or Google Sheets formula.
Percentage decrease formulas
- Decrease % = (Old − New) ÷ Old × 100
- 90 → 81: (90 − 81) ÷ 90 × 100 = 10%.
- New = Old × (1 − Percentage ÷ 100)
- 250 decreased by 12% = 250 × 0.88 = 220.
- Old = New ÷ (1 − Percentage ÷ 100)
- 220 after a 12% decrease = 220 ÷ 0.88 = 250.
- A decrease can never exceed 100%
- Losing everything is a 100% decrease; values below zero need a different comparison.
Why use this percentage decrease calculator
- Answers as you typeNo Calculate button and no page reloads. Change any number and the result updates instantly.
- Shows the workingEvery answer comes with the steps and a plain-English sentence, so you can check it or copy it into homework and reports.
- Spreadsheet formula includedCopy the matching Excel or Google Sheets formula and reuse the calculation on a whole column.
- Private and ad-free workspaceNumbers are calculated on your device. Nothing you type is sent anywhere.
Common uses
- Weight loss. Express progress as a percentage of starting weight.
- Cost cutting. Show how much a bill, budget line or subscription dropped.
- Sales and markdowns. Check the real percentage off a price tag.
- Depreciation. See how much value a car or device has lost.
Need a different calculation? Try the percentage calculator, discount calculator or percentage change calculator, or generate numbers with the random number generator.
Example: tracking weight loss
You started at 92 kg and now weigh 85.1 kg. In “Percentage change”, enter 92 and 85.1: the result is −7.5%, a 7.5% decrease. Many plans suggest measuring progress as a percentage of starting weight, which makes goals comparable between people of different sizes.
What to expect from the result
A decrease from 0 is undefined, and decreases of more than 100% only make sense for values that can become negative, such as profit. For a series of drops, apply each percentage in turn; they do not simply add up.
Percentage Decrease Calculator questions
How do you calculate a percentage decrease?
Subtract the new value from the old value, divide by the old value and multiply by 100. From 90 to 81: (90 − 81) ÷ 90 × 100 = 10%.
How do I decrease a number by a percentage?
Multiply by 1 minus the percentage as a decimal. To take 12% off 250: 250 × 0.88 = 220.
How do I find the original value before a decrease?
Divide the reduced value by 1 minus the percentage as a decimal: 220 ÷ 0.88 = 250.
Is a 20% decrease followed by a 20% increase back to the start?
No. 100 − 20% = 80, and 80 + 20% = 96. The increase is applied to a smaller number, so you end 4% lower.
What is the Excel formula for percentage decrease?
Use =(Old-New)/Old and format as a percentage, or =(New-Old)/Old to get a negative number for decreases.