Formula
A decrease subtracts that share of the starting value:
New value = starting value × (1 − decrease percent)
A 100% decrease reaches zero. A larger decrease is not accepted.
Assumptions
- The decrease is from 0 to 100 percent.
- The starting value may be negative.
Worked example
An 80 starting value decreased by 25% becomes 60.
Input definitions
- Decrease
- The percent removed, from 0 to 100.
- Starting value
- The number before the decrease.
Limitations
Results are rounded for display. This is a classroom calculation, not a measurement from a lab or a financial filing.
Questions
Why stop at 100%?
Removing more than the whole starting value is an increase in the opposite direction. Use the increase page for a percent added.
Is this the same as percent change?
No. Percent change compares two finished numbers. This page applies a decrease you already know.