What if the starting value is zero?
Percent change cannot be computed when the baseline is zero, so the calculator marks the result as undefined.
Step-by-step walkthrough
Percentage Change Calculator Guide
Use this companion guide beside the interactive calculator to make sure you understand the “why” behind every click. Each section includes the classroom explanation, student-friendly language, and quick practice prompts.
Before you start
Collect the data points listed below and double-check their units. Keeping an organized “givens” list is one of the fastest ways to reduce math errors and impress exam graders.
- percent change
- increase
- decrease
Detailed procedure
Step 1
Enter the starting value.
Step 2
Enter the ending value you want to compare against the start.
Step 3
Review the percent change and the raw difference below the inputs.
Teaching & troubleshooting tips
How do I interpret a negative result?
A negative percent change means the ending value is smaller than the starting value, indicating a decrease.