Jet Lag Recovery Calculator

A common rule of thumb is that your body adjusts about one time zone per day. This calculator starts from that baseline and adjusts for direction, since the internal clock resets a little faster heading west than east. For a 6-zone trip you can expect roughly 4 to 6 days of adjustment, depending on which way you flew.

Your internal clock naturally runs slightly longer than 24 hours, so it finds it easier to be delayed than advanced. Flying west delays your clock (you stay up later), which matches that natural drift. Flying east advances it (you must sleep earlier), which works against it. This calculator uses about 1.5 zones per day westward and 1.0 zone per day eastward to reflect that difference.

It subtracts your departure UTC offset from your arrival UTC offset. A positive result means you traveled east (the clock moves forward) and a negative result means you traveled west. If the difference is more than 12 hours, it takes the shorter route around the clock, so flying 14 zones east is treated as 10 zones of delay.

Light is the strongest signal for resetting your body clock. After flying east, seek morning light and avoid bright light late in the evening to shift earlier. After flying west, seek evening light and avoid early-morning light to shift later. The calculator shows the right window for your direction of travel.

No. This tool is for general education and travel planning, not a substitute for professional medical advice. Actual recovery depends on age, sleep quality, flight timing, caffeine, and how strictly you control light exposure. If jet lag seriously disrupts your health or you take time-sensitive medication, talk to a clinician.

You usually cannot eliminate it, but you can shorten it. Shifting your sleep schedule by an hour a day in the days before you fly, getting light at the right times, staying hydrated, and timing naps carefully all help. Short trips of one to two zones often need little or no adjustment at all.