Jet Lag Recovery Calculator
Estimate jet lag severity and recovery time based on time zones crossed and travel direction.
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How to use this calculator
Eastward travel is harder because you lose time and must advance your body clock — each time zone adds roughly 1 full recovery day. Westward travel is easier (gaining time), so each zone adds about 0.67 days. An age multiplier adjusts for the fact that older travelers typically recover more slowly from circadian disruption.
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Count the number of time zones between your departure and destination cities — this is the primary driver of jet lag severity.
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Select your travel direction (eastward or westward) and your age group, as both affect recovery speed.
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Review your severity rating and the recommended adaptation strategy to plan your pre- and post-flight schedule.
Frequently asked questions
Why is flying east worse than flying west?
The human circadian rhythm naturally runs slightly longer than 24 hours, making it easier to delay sleep (westward travel) than to advance it (eastward travel). Going east forces your body to fall asleep and wake earlier than it wants to, which takes more adjustment time.
How can I minimise jet lag before my flight?
Start shifting your sleep schedule 2–3 days before departure in the direction of travel. Stay well hydrated during the flight, avoid alcohol, and get exposure to natural light at the destination as soon as possible after landing.
Does melatonin help with jet lag?
Research supports low-dose melatonin (0.5–3 mg) taken at the target bedtime of the destination for 2–4 nights after arrival. It is most effective for eastward travel. Always consult a healthcare professional before using supplements.
Jet Lag Recovery Calculator — Find Out How Long Your Body Needs to Adjust
How to use the jet lag recovery
Use this jet lag recovery to jet lag severity and recovery time based on time zones crossed and travel direction. Enter your values above and get your result in seconds. The tool is free, works on all devices, and keeps your data private — nothing is stored or shared.
How the jet lag recovery works
The jet lag recovery calculator uses standard formulas used in travel planning, budgeting, and trip logistics. Enter your inputs, and the tool calculates the result instantly in your browser. No server-side processing means your data stays on your device. Results update in real time as you change inputs.
What causes jet lag
Jet lag is a temporary sleep disorder caused by rapid travel across multiple time zones, disrupting your body's internal circadian clock. Your body expects light and dark, hunger and sleep, at specific times — crossing zones rapidly misaligns these cues with the new local time. Symptoms include fatigue, insomnia, difficulty concentrating, digestive upset, and general malaise. Most symptoms resolve as your circadian rhythm gradually synchronises to the new environment.
Recovery timelines and what affects them
The general rule is one day of recovery per time zone crossed for eastward travel, and two-thirds of a day per zone for westward travel. Age matters: travellers over 60 often take 30% longer to adapt than those under 30 due to reduced melatonin production and less circadian flexibility. Flight duration matters too — even short ultra-long-haul flights can cause significant fatigue independent of jet lag, compounding the recovery period.
Jet lag recovery: how it works
This free tool saves time and reduces the chance of manual errors. Enter your values, get an instant result, and use it as a starting point for further analysis or professional consultation.
Who uses this tool?
Anyone who needs a fast, reliable answer uses this tool as a first step. It is designed to be accessible to non-specialists while accurate enough to trust for most everyday purposes.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →