Sleep & wake-up
Jet lag calculator
Enter how many time zones you are crossing and which way you are flying to estimate how many days recovery may take.
A rough rule is one day of adjustment per time zone, and eastward travel is usually harder than westward.
Why direction changes recovery time
Jet lag happens when your internal clock is still set to the time zone you left. A common rule of thumb is about one day of adjustment per time zone crossed. Flying east is usually harder than flying west, because east shortens your day and asks your clock to move earlier, which it resists, while west lengthens the day and is easier to stretch into. This tool uses that difference to estimate your recovery days from the zones you cross and the direction you fly.
| Direction | Effect on your day | Light strategy |
|---|---|---|
| Eastward | Shorter day, clock must move earlier | Morning light, avoid late evening light |
| Westward | Longer day, clock must move later | Evening light, avoid early morning light |
Speeding up the adjustment
Light is the strongest signal for your body clock, so use it deliberately in the direction the table suggests. Shift your meals and sleep toward the new time zone as soon as you arrive, get outside during the day, and avoid long naps that anchor you to the old schedule. Staying hydrated and limiting alcohol on the flight also helps you settle faster.
Frequently asked questions
Why is flying east worse?
East shortens your day and forces your clock to run earlier, which most people's bodies resist. Flying west lengthens the day, and stretching your schedule later is generally easier, so recovery tends to be quicker.
How can I adjust faster?
Use light at the right times for your direction, shift meals and sleep to the new zone immediately, get daytime sunlight and avoid long naps. These signals help your body clock catch up sooner.
Is one day per time zone accurate?
It is a rough guide. Actual recovery varies with age, the trip length, how well you sleep and how consistently you use light. Treat the estimate as a starting point rather than a fixed schedule.