🌙 Night Shift · Zero-Competition Tool
Night Shift Fasting Calculator
The only fasting calculator that correctly handles fasting windows crossing midnight. Built specifically for night workers, shift nurses, security staff, and frequent travelers.
Step 1 — Choose Your Protocol
16:8 is the most popular protocol — fast 16h, eat within 8h.
Step 2 — Personalise Your Schedule
Your eating window starts from this time
🎯 Your Goal
⏱ Time Checkpoints
Your Fasting Timeline
Elapsed-time checkpoints for a 16-hour schedule. These do not measure metabolic changes.
Fast Started
+0hThe clock measures time since your last calories. It does not measure digestion or metabolic changes.
📄 Mayo ClinicEarly Fasting
+2hDigestion and nutrient absorption vary with the meal and the individual.
📄 NIH — Metabolism OverviewBetween Meals
+4hYour body uses a mixture of fuels. Time alone cannot identify your blood glucose or insulin level.
📄 PubMed — Insulin & Glucose DynamicsOvernight Interval
+8hAn overnight interval may include sleep. Glycogen use varies with diet and activity.
📄 Cahill GF Jr — NEJM 197012 Hours Elapsed
+12hTwelve hours is a time checkpoint, not a diagnosis of ketosis. Ketone production varies between people.
📄 Cahill GF Jr — NEJM 197016 Hours Elapsed
+16hSixteen hours does not establish autophagy activation. There is no validated universal human autophagy timer.
📄 Levine & Kroemer — Cell 2008Time checkpoints are educational, not a recommendation to extend your fast.
Why Night-Shift Fasting Is Different
Most fasting apps and calculators assume a standard daytime schedule. If you work nights — starting your shift at 10 PM and sleeping until 2 PM — standard calculators give you nonsensical windows.
Our calculator includes a crossesMidnight detection flag that correctly calculates your eating and fasting windows regardless of when your day starts. Set your “eating start time” to whenever you wake up before your night shift.
💡 Night-Shift 16:8 Example
🕗 Wake up: 7:00 PM
🍽️ Eating window: 7:00 PM – 3:00 AM (8 hours)
🌙 Fasting window: 3:00 AM – 7:00 PM (16 hours, crosses midnight)
Medical Disclaimer
This tool provides estimates for informational purposes only. Always consult a licensed healthcare provider before beginning any fasting protocol — especially if you are pregnant, have a history of eating disorders, diabetes, or any other medical condition.
Sources: Mayo Clinic · NIH · PubMed