MTMasterTool

Percentage Decrease Calculator

Calculate percentage decrease instantly in your browser.

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What this tool does

Calculate percentage decrease instantly in your browser. Negative original values use absolute original magnitude as the denominator; negative results represent change in the opposite direction.

How to use the Percentage Decrease Calculator

  1. Enter or select original value.
  2. Enter or select new value.
  3. Read the calculated result; change any measurement to compare alternatives.

Formula

increase%=100×(new−old)/abs(old); decrease%=100×(old−new)/abs(old)
old
Original value
new
New value

Negative original values use absolute original magnitude as the denominator; negative results represent change in the opposite direction.

Worked example

For percentage decrease calculator, the following measurements illustrate the exact method: Original value: 100; New value: 80.

Inputs

  • Original value100
  • New value80

Result

  • Percentage decrease (%)20

Results explained

Percentage decrease (%)
Percentage decrease (%) from the formula above. Negative original values use absolute original magnitude as the denominator; negative results represent change in the opposite direction.

Frequently asked questions

increase%=100×(new−old)/abs(old); decrease%=100×(old−new)/abs(old)

Negative original values use absolute original magnitude as the denominator; negative results represent change in the opposite direction.

Where mathematically meaningful, yes. Fields specify permitted ranges and undefined operations display an error.

Exact integer calculations use safe integers; decimal calculations use browser floating point, so small rounding differences can occur.

All values remain in your browser and are never uploaded.