Estimate jet lag severity and recovery time from a time zone change.
The body clock adjusts more easily westward, because lengthening a day is easier than shortening one. That asymmetry is why eastward travel takes roughly half again as long to recover from. Recovery takes about a day per time zone eastward, which means a trip shorter than the recovery period is spent entirely jet-lagged.
Jet Lag
Recovery days ≈ time zones crossed ÷ adjustment rate, adjusted for age
Recovery days ≈ time zones crossed ÷ adjustment rate, adjusted for age The body clock adjusts more easily westward, because lengthening a day is easier than shortening one. That asymmetry is why eastward travel takes roughly half again as long to recover from.
Recovery takes about a day per time zone eastward, which means a trip shorter than the recovery period is spent entirely jet-lagged.
This calculator takes 5 inputs: Time zones crossed, Direction of travel, Age, Flight duration, Sleep obtained on the flight. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.