DepartureMap

Jet Lag Recovery Calculator

Enter your origin and destination airports to calculate the time zone difference and get a personalized recovery plan for your trip.

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How Jet Lag Works

Jet lag occurs when your body's internal clock (circadian rhythm) is out of sync with the local time at your destination. Your circadian rhythm is a roughly 24-hour cycle that regulates sleep, hormone production, body temperature, and digestion. It is primarily controlled by light exposure through the suprachiasmatic nucleus in the brain.

When you cross multiple time zones rapidly by air, your body clock remains set to the departure city's time. This mismatch causes symptoms like daytime fatigue, nighttime insomnia, difficulty concentrating, digestive issues, and general malaise.

East vs. West: Why Direction Matters

Traveling eastward requires you to advance your body clock — falling asleep earlier and waking up earlier than usual. Most people find this harder because the human circadian rhythm naturally runs slightly longer than 24 hours, making it easier to stay up late (as westward travel requires) than to go to bed early.

As a rule of thumb, recovery from eastward travel takes about 1 day per 1.5 time zones crossed, while westward travel takes about 1 day per 2 time zones. The calculator above uses this formula along with your arrival time to generate personalized advice.

The Role of Light Exposure

Light is the most powerful tool for resetting your circadian rhythm. When traveling east, morning sunlight at your destination helps advance your clock. When traveling west, afternoon and evening light delays it. Avoiding light at the wrong times is equally important — wearing sunglasses or staying indoors during the "wrong" part of the day can speed up your adjustment.

Frequently Asked Questions

How long does jet lag last?
Jet lag typically lasts 1 day for every 1–1.5 time zones crossed when traveling east, and 1 day per 2 time zones when heading west. A flight from London to Bangkok (6 hours east) may take 4–6 days to fully adjust, while the return trip might only take 3–4 days. Symptoms like fatigue, insomnia, and difficulty concentrating usually peak on days 2–3 and gradually improve.
Is jet lag worse flying east or west?
Yes, flying east is generally harder on the body. When you travel east, you need to advance your internal clock — go to bed earlier and wake up earlier — which is more difficult than delaying it. Westward travel lets you stay up later, which most people find easier to adapt to. This is why the same route can feel very different depending on direction.
What is the best way to recover from jet lag?
The most effective strategies are: (1) Get sunlight at the right times — morning light when traveling east, afternoon light when traveling west. (2) Adjust meal times to the local schedule immediately. (3) Stay hydrated and avoid alcohol/caffeine for the first 24 hours. (4) Consider low-dose melatonin (0.5–3 mg) at the destination's bedtime for 3–4 nights. (5) Gradually shift your sleep schedule before departure if possible.
Can you prevent jet lag?
You can significantly reduce jet lag by preparing before your trip. Start shifting your sleep schedule 30 minutes per day toward the destination time zone several days before departure. Stay well-hydrated during the flight, avoid heavy meals, and set your watch to the destination time when you board. On arrival, immediately adopt local meal and sleep times and seek sunlight at the optimal times for your travel direction.
Does jet lag get worse with age?
Research suggests that jet lag can feel more intense as you get older because the body's circadian clock becomes less flexible. The suprachiasmatic nucleus (the brain's master clock) produces less melatonin with age, making it harder to reset. However, good preparation, light exposure timing, and consistent recovery habits can help travelers of any age minimize jet lag symptoms.

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Popular Long-Haul Routes

These popular routes cross multiple time zones — use the calculator above to plan your jet lag recovery.

London to BangkokNew York to TokyoSingapore to LondonDubai to SingaporeSydney to DubaiLos Angeles to TokyoHong Kong to LondonBangkok to Sydney

The DepartureMap Jet Lag Recovery Calculator helps travelers estimate recovery time and plan for time zone changes on any flight. Results are based on the widely-used rule of 1 day per 1.5 hours eastward and 1 day per 2 hours westward, combined with arrival-time-specific advice for light exposure, sleep scheduling, and meal timing.

Recovery times are estimates and may vary based on individual factors including age, sleep habits, fitness level, and prior travel experience. Consult a healthcare professional for personalized medical advice about jet lag management.