Jet Lag Calculator
Predict your jet lag severity & get a personalised recovery plan.
How to use the jet lag calculator
Jet lag hits when your body clock is out of sync with your destination's time zone — generally worse flying east than west. This tool estimates how many days you'll need to adjust and when to shift your sleep.
Beat jet lag faster
- Adjust before you fly — shift bedtime an hour toward your destination for a few days.
- Chase the light — morning light helps after flying east; evening light after flying west.
- Stay hydrated, limit alcohol, and get on local time the moment you land.
- Short naps only (20-30 min) to avoid prolonging the adjustment.
How many days to adjust, by time zones crossed
| Time zones crossed | Flying west (about 1.5 h/day) | Flying east (about 1 h/day) |
|---|---|---|
| 2 | about 1 day | about 2 days |
| 3 | about 2 days | about 3 days |
| 5 | 3 to 4 days | about 5 days |
| 8 | 5 to 6 days | about 8 days |
| 11 | 7 to 8 days | about 11 days |
Adaptation rates come from the CDC Yellow Book chapter on jet lag disorder, which gives an average rate of adaptation of 1.5 hrs/day for westward travel and 1 hr/day for eastward travel, and defines jet lag as following travel across at least two time zones. The day counts here are that stated rate applied to the number of zones you cross, so treat them as planning estimates, not a clinical prediction. Rates verified 3 September 2026.
Jet Lag Calculator FAQ
How long does jet lag last?
The CDC puts the body clock’s average rate of adaptation at about 1.5 hours per day travelling west and 1 hour per day travelling east, so an eight-hour time shift takes roughly five to six days westbound and about eight days eastbound. Eastward travel is the harder direction because it is easier to delay the circadian rhythm than to advance it.
What is the fastest way to beat jet lag?
Shift your sleep before you fly, get sunlight at the right times, and adopt local time immediately.
