Percentage Change Calculator
Enter an original value and a new value to calculate the signed relative change locally.
A QUICK WALKTHROUGH
How to use this tool
- Enter the original value.
- Enter the new value.
- Review the signed percentage and formula.
Formula and baseline
Percentage change is (new − original) ÷ original × 100. The original value is the baseline and cannot be zero.
Signed result
A positive result means the signed relative change is upward; a negative result means it is downward. The sign is relative to the original value, so negative baselines are handled mathematically rather than treated as absolute magnitudes.
Local calculation
Inputs are calculated in your browser and are not uploaded or stored.
Removal efficiency
Removal efficiency = (influent − effluent) ÷ influent × 100. Use the same metric and unit for both values. Negative results mean the effluent is higher. This does not establish regulatory compliance or pollutant load change. Removal efficiency is undefined when influent is zero. Use nonnegative influent and effluent values. EPA: https://www.epa.gov/sites/production/files/2015-10/documents/owm0013.pdf
GOOD TO KNOW
Common questions
What does the sign mean?
The sign comes from (new − original) ÷ original. It describes the direction relative to the signed original baseline.
Can the original value be zero?
No. Division by zero makes percentage change undefined; the calculator asks for a nonzero original value.