Percentage Decrease Calculator
Enter values to calculate percentage decrease with a clear result.
Calculate
Enter values and select Calculate.
How it works
Percentage decrease = (original value − new value) ÷ original value × 100. Original value must be greater than zero and new value cannot exceed it.
Worked examples
- 100 to 80: 20% decrease
- 250 to 200: 20% decrease
Frequently asked questions
Is this calculator free?
Yes. You can use it without paying or creating an account.
Does it work on a phone?
Yes. The page adapts to small and large screens.
Can I enter zero?
Where zero is mathematically valid, the calculator accepts it.
What happens if I enter an invalid value?
You will see a clear message explaining what to correct.
Does the calculation run in my browser?
Yes. The calculator runs with JavaScript on your device.
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Last updated: October 17, 2026