How to use the Percentage Change Calculator
Enter the original and new values. Percentage change is the difference divided by the original value. Enter the known values, choose any required mode or unit, and calculate the result. Review the labels and units before relying on the answer.
What this calculator does
Calculate percentage increase or decrease from an old value to a new value. It is intended to make the calculation transparent and repeatable: you provide the known values, the calculator applies the relevant relationship, and the result is shown with the units or labels used by the tool.
When this tool is useful
Use the Percentage Change Calculator when you need a quick, repeatable check and already have the inputs requested by the page. It is useful for comparing scenarios, checking hand calculations, planning a task, or understanding how changing one input affects the result.
How the calculation works
Percentage change is (new − old) ÷ old × 100.
Practical example
For example, a value increasing from 80 to 100 is a 25% increase because the 20-point change is measured against the original 80.
Things to keep in mind
- Check units and input labels before calculating.
- Keep enough decimal precision during the calculation and round the final answer to a level appropriate for your use.
- Use the result as a practical aid and verify it against authoritative requirements when precision has legal, safety, financial, or professional consequences.