Jet Lag Recovery Calculator

Travel Direction
Are you flying east (e.g., India → Europe/USA East) or west (e.g., India → USA West/Australia)? Eastbound travel is harder on your body clock.
Count the hour difference between your home city and destination. E.g., Kolkata to London = 5.5 hrs; Kolkata to New York = 10.5 hrs.
5.5
1 12
Age Group
Older adults generally take longer to recover from jet lag. Select your group: Under 30 / 30–60 / Over 60.
Sleep Flexibility
How easily can you adjust your sleep schedule?
Chronotype (Sleep Preference)
Are you a Morning person (early riser), Evening person (night owl), or Neither? This affects how easily your body clock shifts.
Can you start adjusting before travel?
Will you shift your sleep schedule 4 hours earlier the night before your flight?
Your Estimated Jet Lag Recovery Time is:

Westbound travel is generally easier on your body clock. Your internal rhythm naturally runs slightly longer than 24 hours, making delays easier to absorb. Morning light at your destination will help anchor your new schedule.

This is a moderate time zone shift. Your body clock should advance without major disruption. Get bright morning light at your destination and avoid late-night screen exposure on arrival.

You are in the hardest recovery zone. Research shows that a shift of 7–9 hours eastbound pushes your body clock near its adaptation limit — called the jet lag separatrix — causing internal clock cells to temporarily desynchronise. Consider the two-step method next time: shift your sleep 4 hours earlier the night before departure to cut recovery time by roughly 45%.

Excellent. The two-step pre-adaptation strategy is backed by peer-reviewed research in model animals (Kori et al., 2017). By splitting your shift across two days, your SCN clock cells stay synchronised and avoid the desynchrony that makes 7–9 hour eastbound travel so difficult. Your estimated recovery is significantly shorter as a result.

With a shift this large, your body clock may adapt by going the long way around — delaying rather than advancing — which is actually more natural for your circadian system. Give yourself extra recovery days on arrival and prioritise sleep timing over total sleep duration.

Clinical tips

⚠ Night owls find eastbound travel harder. Your natural tendency to delay your body clock works against an eastbound phase advance. Consider starting light exposure earlier 2–3 days before departure.

⚠ Circadian adaptability decreases with age. Allow an extra buffer day before any important commitments at your destination.

💡 You are eligible for the two-step method. Re-run this calculator with pre-adaptation set to Yes to see your reduced recovery estimate.

💡 Consistent sleep and wake times, morning sunlight, and avoiding alcohol on travel days are the most evidence-supported ways to speed circadian recovery.

This calculator uses recovery estimates derived from a peer–reviewed multi–oscillator circadian model published in Scientific Reports (Kori, Yamaguchi & Okamura, 2017, DOI: 10.1038/srep46702). Results are indicative only and do not constitute medical advice.