Frequently Asked Questions
Common questions about percentage calculations and about how this site works.
About the calculator
The calculator solves for whichever field you leave empty. Fill in any two of base, percentage and result, and the third appears as you type — there is no button to press.
Everything runs in your browser. The numbers you enter are never transmitted anywhere, which also means the tool keeps working if your connection drops after the page has loaded.
Frequently Asked Questions
- Which two fields should I fill in?
- Any two. The calculator works out which value is missing and solves for it, so you can use the same form to find a percentage, a part or a total.
- How do I switch between calculation types?
- Use the tabs above the form: percentage of a number, what percent one number is of another, increase or decrease, and percentage change between two values.
- Can I use commas for decimals?
- Yes. Pick your separator in the header. The choice is saved on your device and applies to both input and results.
- Is the site available in other languages?
- The calculator is available in English, Portuguese, Spanish, French, German and Italian. Use the language selector in the header.
- Does it work on a phone?
- Yes. The layout adapts to small screens and the number fields open a numeric keypad on mobile devices.
- How precise are the results?
- Calculations use standard double-precision floating point and results are rounded for display. For accounting work, round explicitly at the step your rules require rather than relying on the displayed value.
- How do I report an error?
- Email franfactory.store@gmail.com with the numbers you entered and what you expected. Reproducible reports get fixed quickly.
- Is the calculator free to use?
- Yes, entirely free and with no account required.