UtilibyJet Lag Calculator
Estimate your recovery time and get personalized tips to beat jet lag. Free, private and no sign-up.
How to use this free jet lag calculator online
- Enter your departure and arrival time zones. If you don't know the UTC offset, search for "current time in [city]" to find it.
- Select whether you're flying east or west.
- Enter your usual bedtime at home. This helps personalize the melatonin timing advice.
- Read your estimated recovery time and personalized tips below.
Why eastward travel is harder than westward
Your body's internal clock (circadian rhythm) naturally runs slightly longer than 24 hours, making it easier to delay sleep than to advance it [citation:8]. When you fly east, you need to advance your clock — go to sleep earlier and wake up earlier. This runs against your natural tendency. When you fly west, you need to delay your clock, which feels more natural.
As a rule of thumb, recovery takes about one day per time zone crossed [citation:4][citation:18]. But eastward travel can take longer, roughly 1 hour per day of adjustment, while westward travel adjusts at about 1.5 hours per day [citation:8].
How to beat jet lag: evidence-based tips
Before you travel
- Start shifting your sleep schedule 2–3 days before departure. If flying east, go to bed 1 hour earlier each night. If flying west, go to bed 1 hour later [citation:8][citation:17].
- Be well rested. Starting a trip already sleep-deprived makes jet lag worse [citation:18].
- If your trip is short (under 3 days), consider staying on home time for meals and sleep rather than trying to adapt [citation:2].
During the flight
- Stay hydrated. Dehydration worsens jet lag symptoms [citation:8].
- Avoid alcohol and caffeine. Both disrupt sleep and cause dehydration [citation:2][citation:18].
- Sleep if it's nighttime at your destination. Stay awake if it's daytime there [citation:9].
- Walk around periodically to reduce stiffness and fatigue [citation:18].
After you arrive
- Get sunlight during the day. Light is the strongest signal to reset your body clock [citation:4][citation:18].
- Avoid lengthy daytime naps. Short naps (15–20 minutes) can help alertness without disrupting nighttime sleep [citation:8].
- Follow the destination's meal and sleep times from day one [citation:2].
Melatonin: how and when to use it
Melatonin can help reset your body clock, but timing is critical. Taking it at the wrong time can make jet lag worse [citation:2][citation:9].
- Dose: 0.5 mg to 5 mg is typical. Higher doses (5 mg) help you fall asleep faster but aren't more effective for shifting your clock [citation:9].
- Timing for eastward travel (phase advance): Take melatonin in the afternoon or early evening at destination time. This helps advance your clock. The CDC recommends 0.5 mg about 4.5 hours before your usual sleep onset [citation:10].
- Timing for westward travel (phase delay): Take melatonin in the morning at destination time if you need to delay your clock [citation:20].
- Avoid taking melatonin at the wrong time. Morning melatonin can cause sleepiness when you need to be awake [citation:9].
Always consult your doctor before taking melatonin, especially if you take other medications [citation:2].
Frequently asked questions
How long does jet lag last?
On average, recovery takes about one day per time zone crossed. A 6-hour time difference may take roughly 3–6 days to fully adjust, depending on direction and individual factors [citation:4][citation:18].
Is jet lag worse flying east or west?
Eastward travel is generally harder because it requires advancing your body clock, which runs counter to your natural tendency to delay sleep [citation:8].
Does melatonin really work for jet lag?
Yes, studies show melatonin can reduce jet lag symptoms, especially for eastward travel and trips crossing 5+ time zones. But timing is critical — taking it at the wrong time can backfire [citation:9].
What's the best way to reset my sleep schedule after travel?
Get morning sunlight, wake up at a consistent time, and avoid long daytime naps. Your wake-up time is the most powerful anchor for your circadian rhythm [citation:11].
Is this jet lag calculator accurate?
It provides evidence-based estimates using scientific research on circadian rhythms. Individual results may vary. It is not medical advice [citation:8].