The jet lag calculator estimates how many days it will take to recover from crossing multiple time zones, and gives tips to minimize symptoms.
Minimizing Jet Lag
Jet lag happens when your circadian rhythm (internal body clock) is out of sync with the local day-night cycle. Your body can shift roughly 1-2 hours per day, so a 6-hour eastward jump can take 4-6 days to fully resolve.
Eastward flights are harder
Flying east means losing time — your body wants to sleep when it's morning. The maximum difficulty is around 9-12 hours east (e.g., New York to Japan). Flying west is easier because you're extending your day, which feels more natural to most people.
Practical tips that actually work
Melatonin (0.5-3mg) taken at your destination's bedtime helps reset your clock — timing matters more than dose. Bright light exposure in the morning at your destination accelerates adaptation. Hydration helps, but alcohol and heavy meals on flights worsen symptoms. If your trip is under 3 days, consider staying on home time instead of adapting.
Frequently Asked Questions
How long does jet lag last?
Roughly 1 day per time zone crossed when flying east, and 0.75 days per zone when flying west. A 6-hour eastward shift typically causes 4-6 days of symptoms. Individual variation is significant — some people adapt faster.
Is eastward or westward jet lag worse?
Eastward travel is harder for most people. You're losing time, so your body wants to sleep during morning hours at your destination. Westward travel extends your day, which feels more natural.
Does melatonin help with jet lag?
Yes, when taken correctly. 0.5-3mg of melatonin at your destination's bedtime (not before flying) helps signal your body to shift its clock. Timing matters more than dosage. Consult a doctor if you have concerns.
How can I minimize jet lag?
Gradually shift sleep times 2-3 days before departure, stay hydrated on the flight, avoid alcohol, get morning light at your destination, and stay awake until local bedtime on arrival day (even if exhausted).
Is this calculator free?
Yes, completely free and no signup required.