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Jet Lag Recovery Calculator
Estimate recovery days and get a 3-day light, sleep, and meal plan based on your direction of travel.
What jet lag actually is
Jet lag is the gap between your circadian clock and the local clock at your destination. Your body wakes, eats, and gets sleepy on home time, while the world around you runs on local time. Symptoms are worst when the two are most out of sync (mid-afternoon slumps, 3 a.m. wide-awakeness). The body resyncs at roughly one time zone per day — eastward travel is harder than westward because it asks you to fall asleep earlier than your clock wants.
How to use it
Enter the UTC offsets of your origin and destination (Google has them; e.g. "Tokyo UTC offset"). Set your departure local time and the flight's block-to-block duration. The calculator gives you the expected recovery window, your arrival local time, and a 3-day plan for light exposure, sleep, and meals — the three biggest levers for resyncing your body clock.
Your 3-day recovery plan
Based on direction. Light is the strongest signal to your body clock; sleep and meal timing reinforce it.
| Day | Light | Sleep | Meals |
|---|---|---|---|
| 1 | — | — | — |
| 2 | — | — | — |
| 3 | — | — | — |
How the math works
Time difference = destination UTC offset − origin UTC offset. Recovery ≈ 1 day per timezone crossed (rounded up), capped by perception around 7-10 days. Arrival local time = departure (origin local) + flight duration + (destination − origin) UTC offset difference. The light/sleep/meal advice follows the consensus from circadian-rhythm research; details from your sleep doctor or trip planner take priority.