How many days does it take by time difference?
Estimates from the calculator for an adult; kids usually follow a similar timeline when they get daylight at the right times. "Head start" means shifting 1 hour a day for 2 days before you fly (kids shift in smaller steps).
| Time difference | East, no prep | East, 2-day head start | West, no prep | West, 2-day head start |
|---|---|---|---|---|
| 2 hours | 2 | 1 | 2 | 1 |
| 3 hours | 3 | 1 | 2 | 1 |
| 4 hours | 4 | 2 | 3 | 2 |
| 5 hours | 5 | 3 | 4 | 2 |
| 6 hours | 6 | 4 | 4 | 3 |
| 7 hours | 7 | 5 | 5 | 4 |
| 8 hours | 8 | 6 | 6 | 4 |
| 9 hours | 9 | 7 | 6 | 5 |
| 10 hours | 10* | 8* | 7 | 6 |
| 11 hours | 9* | 8* | 8 | 6 |
| 12 hours | 8* | 7* | 8* | 7* |
What makes jet lag last longer?
- Flying east, especially 7+ hours.
- Getting bright light at the wrong time of day (for example early-morning sun right after flying east).
- Long or late naps, and sleeping in.
- Teens: their body clocks resist moving earlier.
- Short, broken sleep on the plane (one night of lost sleep is recovered quickly; the clock shift takes longer).
How can you shorten it?
- Start shifting bedtimes 2–3 days before you fly (adults 1 hour a day, kids 15–30 minutes).
- Switch to destination time when you board.
- Get outdoor light in the right windows after landing and avoid it in the wrong ones.
- Keep naps short and early; hold a fixed wake-up time.
- Use the free calculator for exact times for your trip.
How do you know jet lag is over?
- Kids fall asleep within about 20–30 minutes of local bedtime.
- No more 3–5 AM wake-ups or late-night alertness.
- Normal appetite at local meal times and no afternoon crash.
Frequently asked questions
How long does jet lag last for a 2-year-old?
Often 3–6 days after a big time change, similar to adults. Keeping naps on local time and getting daylight helps.
Do kids get over jet lag faster than adults?
Sometimes, but research in children is limited. Kids who get lots of outdoor daylight and keep a fixed wake time often adjust as fast as their parents.
How long is jet lag after flying from the US to Europe?
About 6–8 days without preparation for a 6–8 hour eastward shift, or 4–6 days with a 2-day head start.
How long is jet lag after flying from the US to Asia?
Most US–Asia trips feel like a westward shift of 7–11 hours, about 5–8 days to adjust. Coming home eastward is often slower.
Route plans
- New York → London
- New York → Athens
- Los Angeles → Tokyo
- Denver → Rome
- Chicago → Tokyo
- Seattle → Paris
- Miami → Paris
- Atlanta → Paris
More guides
- With a baby (0–12 months)
- With a toddler (1–3)
- With kids 4–8
- With teens
- Flying east with kids
- Flying west with kids
- Melatonin for kids
- Time difference chart
- Jet lag coming home
- Sleep kit checklist
- Jet lag not working?
- Jet lag gear for kids
- Travel insurance for families
Sources
- CDC Yellow Book 2026: Jet Lag Disorder. US Centers for Disease Control and Prevention guidance for travelers and clinicians.
- Eastman CI, Burgess HJ. How to travel the world without jet lag. Sleep Med Clin, 2009. The light-timing and pre-flight shifting method this calculator follows.
- Burgess HJ et al. Preflight adjustment to eastward travel: 3 days of advancing sleep with and without morning bright light. J Biol Rhythms, 2003. Shifting sleep 1 hour a day before an eastward flight.
How we turn this research into plans: methodology.
Not medical advice. General sleep and travel guidance based on published circadian research. Ask your doctor or pediatrician about melatonin or other supplements, pregnancy, medications or health conditions. Never give melatonin to babies or toddlers.