Fasting Calendar Calculator

This calculator handles three distinct fasting patterns with different hour logic for each, so the "effective fasting hours per day" behind the scenes isn't a single formula — it's a lookup based on which fast type you select. Intermittent fasting uses the fasting-window hours you enter directly (e.g., 16 for a 16:8 pattern). A full-day fast is always treated as 24 fasting hours, since no eating window applies. A Daniel fast — the biblical partial fast that restricts diet rather than eliminating it — is counted as roughly 14 hours of "significant dietary restriction" as a rough proxy, since it isn't a true hours-based fast at all; that number is a stand-in, not a measured quantity.

Total fasting days comes from your calendar duration converted to weeks, multiplied by your chosen fasting days per week and rounded to a whole day. Meals skipped only applies cleanly to intermittent and full-day fasts: a full-day fast skips all 3 meals, an intermittent fast skips 0-2 meals depending on how long the window is (skipping fewer meals below 14 hours, more as the window stretches past 20), and a Daniel fast is treated as replacing meals rather than skipping them, so it always reports zero meals skipped even though the diet itself is restricted all day. Know before you rely on this: the hour figures for full-day and Daniel fasts are fixed estimates baked into the calculator, not something you can fine-tune, and the eating-window figure only means something for the intermittent option.