About Free Fasting Calc
Last reviewed: 19 October 2026
Free Fasting Calc is a free set of intermittent fasting tools with plain-English guides. You can work out your eating window, time a fast, check whether a drink or supplement breaks it, and plan around shift work, your cycle or Ramadan. There is no account, no sign-up and no advertising.
How we check our figures
AI tools check every figure on the site against its official source before a page goes live, and the date of each check is recorded. Official sources here means health bodies, clinical guidelines, medicine labels, official food data and peer-reviewed studies. If a figure can't be checked, it doesn't go on the site. Figures that can change are checked again on a schedule.
Pages show the facts plainly rather than with lists of references. If you think a figure is wrong, please tell us through the contact page: we check it against the source and correct it.
The rules every page follows
- Calculators use published formulas, and each tool explains how it works.
- Health claims say how strong the evidence is, and no page claims fasting treats or cures anything.
- Tools refuse to show unsafe targets and point to support instead.
- No before-and-after pictures, no guaranteed results and no "lose this much by this date" promises.
Who fasting is not for
Intermittent fasting suits some people and is a poor idea for others. If you are pregnant or breastfeeding, under 18, have had an eating disorder, or take medicine for diabetes, talk to a doctor first rather than deciding from a calculator. Read the medical disclaimer before relying on anything here.
Contact
Corrections and questions are welcome at contact@freefastingcalc.com.