Free Percentage Calculator that works offline
Handle three common percentage questions in one focused calculator: a percentage of an amount, one value as a percentage of another, and relative change between a starting and ending value.
What this percentage calculator does
These questions use different formulas even though all mention percent. Making the mode explicit reduces errors, and zero-denominator checks prevent the interface from presenting Infinity as a useful answer.
How to use the Percentage Calculator
- Enter or paste two numeric values and one of the three percentage modes into the tool.
- Adjust the available options so they match the format and result you need.
- Choose Calculate and review the percentage or numeric result with controlled precision before using it.
- Copy or download the result, then clear the page if the input was sensitive.
Common uses
- Calculating discounts and markups
- Comparing a part with a total
- Measuring growth or decline
- Checking spreadsheet percentage formulas
Private processing and offline access
This tool does not submit your input to a conversion server. Processing takes place inside the browser using local JavaScript and standard Web APIs. After the PWA has been installed or cached, the page and its core features remain available without an internet connection. Closing or clearing the page removes unsaved input; the tool does not create an account or cloud history.
Tips for accurate results
- Percentage points and percentage change are different concepts.
- The change formula uses the absolute starting value as denominator.
- Financial or legal decisions may require specific rounding rules.
Frequently asked questions
Does this tool upload my data?
No. Percentage Calculator processes its input in the current browser and does not submit it to a conversion API.
What input does the Percentage Calculator accept?
Finite positive or negative values are accepted. Division modes reject a zero denominator because the result would be undefined.
Can I use this tool offline?
Yes. Once the Offline Tools PWA has cached the page, the core feature works without an internet connection.