What does this tool do?
Jet lag is the mismatch between your body clock and local time. Most travellers adjust about one time zone per day going east and a little faster going west, because the internal clock naturally runs slightly longer than 24 hours.
The Formula
Recovery days ≈ time zones × 1.0 (east) or × 0.75 (west)Frequently Asked Questions
Is jet lag worse flying east or west?
Eastward travel is usually harder because the body clock has to advance, which fights its natural tendency to run long. Westward travel is often easier and slightly faster to recover from.
Can light exposure speed up adjustment?
Yes. Morning light helps advance the clock after eastward travel, while evening light helps delay it after westward travel. Keep the pattern consistent for a few days.