Jet Lag Calculator

Estimate how many days it takes to adjust after crossing time zones.

Estimate how many days you need to beat jet lag.

Time zones crossed

Direction of travel

Rule of thumb: eastward travel takes about one day to adjust per time zone crossed; westward travel is easier, about one day per one and a half zones.

Examples

Trip	Time zones and direction	Estimated adjustment
New York → Paris	6, eastward	about 6 days
Paris → New York	6, westward	about 4 days
London → Dubai	4 (UK winter), eastward	about 4 days
Paris → Tokyo	8 (European winter), eastward	about 8 days
Tokyo → Paris	8, westward	about 5 days
New York → Los Angeles	3, westward	about 2 days

These are rule-of-thumb estimates: many travellers feel normal sooner, especially on short trips. Find the exact number of zones for your dates with the Time Zone Converter.

How it works and tips

How it works

Enter the number of time zones you cross and the direction of travel. The estimate uses a common rule of thumb: about one day to adjust per time zone when flying east, and about one day per one and a half zones when flying west. The calculator counts up to 12 zones, the most a body clock can really shift. This matches the average adaptation rates given by the US Centers for Disease Control and Prevention: about 1 hour a day after flying east and about 1.5 hours a day after flying west (CDC Yellow Book: Jet Lag Disorder).

Tips to adjust faster

Switch to the destination’s meal and sleep times as soon as you board.
Get daylight in the morning after flying east, and in the late afternoon after flying west.
Keep naps short (20–30 minutes) and before mid-afternoon local time.
Drink water during the flight and limit alcohol and late caffeine.
Ask a doctor or pharmacist before using sleep aids or melatonin.

Related tools

To find how many time zones separate two cities on your travel dates, including daylight saving changes, use the Time Zone Converter. To work out how long the flight itself takes once the offsets are accounted for, see the Flight Duration Calculator.