Jet Lag Recovery Duration Calculator
Estimate how many days jet lag will affect you based on time zones crossed, flight direction, and age.
Get tips to recover faster.
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Jet Lag Recovery Time
Jet lag occurs when your internal body clock (circadian rhythm) is out of sync with local time. It affects nearly everyone who crosses multiple time zones rapidly.
How the calculation works:
The general rule of thumb:
Recovery Days ≈ Time Zones Crossed × Direction Factor × Age Factor
- Eastward travel is harder than westward. Flying east shortens your day, which is harder to adapt to.
- Eastward factor: ~1.0 day per time zone
- Westward factor: ~0.7 days per time zone
- Age plays a significant role — older adults recover more slowly.
Example: Flying from New York (Eastern) to London (GMT) — 5 time zones eastward:
- Estimated recovery: 5 × 1.0 = ~5 days
Flying from London to Los Angeles — 8 time zones westward:
- Estimated recovery: 8 × 0.7 = ~5–6 days
Common symptoms and their timeline:
| Symptom | Onset | Duration |
|---|---|---|
| Daytime fatigue | Immediate | 2–5 days |
| Insomnia / early waking | Night 1 | 3–7 days |
| Difficulty concentrating | Day 1 | 2–4 days |
| Digestive issues | Day 1 | 2–3 days |
| Mood changes / irritability | Day 1–2 | 2–5 days |
Recovery tips — proven to work:
Before the flight:
- Adjust your sleep time 2–3 days before departure (earlier for westward, later for eastward).
- Stay well hydrated and avoid alcohol on the plane.
- Select flights that arrive in the evening local time — easier to go to bed.
After arrival:
- Force yourself onto local time immediately — stay awake until at least 9–10 PM local time.
- Get sunlight exposure in the morning if you flew east; in the afternoon if you flew west.
- Melatonin (0.5–3 mg) taken at local bedtime can help reset your clock 2–3 days faster.
- Short naps (20–30 minutes max) are fine; long naps will make recovery harder.
- Avoid caffeine after 2 PM local time at your destination.
Factors that worsen jet lag:
- Flying through more than 8 time zones
- Older age (slower circadian adaptation)
- Sleep deprivation before travel
- Alcohol and dehydration during flight
- Remaining in low-light environments all day after arrival