Jet Lag Calculators & Planners

Jet lag calculatorScore, direction and the estimated adjustment time for your route.Time differenceThe DST-correct clock difference between two places, right now.Body clockA 24-hour ring of your inner clock: CBTmin, biological night, melatonin onset.Light plannerSeek/avoid light windows per adjustment day, in destination time.East / westWhy advancing the clock (eastbound) is usually the harder direction.Flight sleep plannerOnboard sleep and stay-awake windows in home and destination time.Jet lag durationHow many days to full adjustment — an estimate, direction-modulated.Adjustment plannerA day-by-day plan combining light, sleep and timing.

Eight free calculators for jet lag, time zones, light and sleep — each an estimate, not medical advice, and each showing its working. They share one chronobiology engine, so a trip you enter in one tool carries over to the next.

Frequently asked questions

Are the calculators free?

Yes. They run entirely in your browser, need no login, and send no trip data to a server. A shareable result link carries only your route.

Which tool should I start with?

Start with the jet lag calculator for a score and a plan, then open the light planner for the timed-light windows that reset your clock fastest.

Are the results medically validated?

No. The scores are transparent heuristics built on established chronobiology and shown with their model version. For health questions, consult a doctor or pharmacist.

jetlag.info offers general orientation for adjusting your sleep–wake rhythm — not a medical diagnosis or treatment. The jet-lag score is a transparent heuristic, not a validated measurement. For health questions, consult a medical professional.