Jet Lag Calculator

The Jet Lag Calculator estimates the time-zone offset difference between departure and arrival and converts that difference into adjustment days and hours using a 1.5-hour-per-day assumption.

It normalizes the offset difference to the shortest path within a 24-hour cycle:

$\text{Offset difference}=((\Delta+12)\bmod24+24)\bmod24-12$ $\text{Adjustment days}=\operatorname{ceil}\left(\frac{|\text{Offset difference}|}{1.5}\right)$

Example

A 6-hour time-zone shift produces ceil(6 / 1.5) = 4 adjustment days, or 6 modeled adjustment hours per the output contract.

Questions

Does travel direction change the result?

The current calculation accepts a direction field in its type but derives the normalized difference from offsets. It does not apply separate east- and westbound physiology.

Is this medical advice?

No. It is a travel-planning estimate and does not prescribe sleep, light, or medication.

Does it account for flight duration?

No. It uses time-zone offsets only.

Limitations

Actual adjustment varies by sleep schedule, light exposure, travel timing, health, and destination routine.