Is fasting safe for everyone?

Not necessarily—ask your clinician if you have medical conditions or take medications.

Does daylight saving affect this?

Use local wall-clock times consistently.

What about hydration?

Water and non-caloric drinks are commonly allowed—pick a plan that fits you.

Intermittent Fasting Calculator

How to Use

Choose a fasting method, enter last meal time, and set wake/sleep preferences. The calculator shows a daily schedule and a weekly grid for 5:2/ADF.

Formula

Eating start = fast start + fast duration (mod 24h); eating end = eating start + eating window.

Intermittent fasting schedule guide (timing-first)

Use this page to plan fasting windows, align meals with sleep and training, and generate a simple 7-day schedule for methods like 5:2 and ADF.

What this calculator does best

Intermittent fasting is mostly a timing system. This page focuses on schedule: when your fast begins, when you break it, and how your eating window fits around wake and sleep. It also supports weekly-pattern approaches like 5:2 and alternate-day fasting.

Choosing a protocol by experience level

Beginner: 12–16 hours for consistency and adherence.
Intermediate: 18–20 hours if energy and sleep remain stable.
Advanced: OMAD or longer fasts only if routine is stable and recovery is good.

Why the clock diagram matters

A 24-hour visual makes your plan obvious at a glance. If the eating window overlaps sleep, late-night calories can hurt adherence and recovery. Use the diagram to shift meal timing earlier when possible.

Intermittent Fasting Calculator

Essential fields

24-hour schedule

Weekly schedule

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