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Jet Lag Calculator (Recovery Days)

Enter the time zones crossed and the direction to estimate jet lag recovery time.

By TheCalcTools Updated Formula checked and tested

Your numbers

Your results

Estimated days to adjust
Estimated days to adjust
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Rounded up
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Hours of shift left on arrival
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Light tip
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Jet Lag Calculator (Recovery Days) by TheCalcTools

How the Jet Lag Calculator (Recovery Days) works

Your circadian clock shifts gradually: research summarised by Waterhouse and colleagues suggests roughly 1 hour per day after flying east and about 1.5 hours per day after flying west. Westward trips are easier because the natural body clock runs slightly longer than 24 hours.

Shifting your bedtime by an hour a day for a few days before departure (earlier for eastward trips, later for westward) does part of the adjustment in advance.

These are averages: age, light exposure, sleep before the flight, alcohol and caffeine all change the real recovery time.

The formula

Days ≈ (time zones − pre-trip shift) ÷ adjustment rate per day

Worked example

Using the default values shown in the calculator:

Time zones crossed (hours of difference)7
Direction of travelEastward (clock moves forward)
Days you shift your sleep by 1 hour before leaving0
Body clock adjustment per day eastward (hours)1
Body clock adjustment per day westward (hours)1.5
  1. 7 time zones eastward at 1 hour per day: 7.0 days.
  2. Shifting your sleep for 3 days before leaving would leave 4 hours to adjust on arrival.

Result:

Estimated days to adjust7.0
Rounded up7
Hours of shift left on arrival7.0
Light tipGet morning light and avoid late evening light at your destination

Frequently asked questions

Is it worse flying east or west?

Usually east. Advancing the body clock is harder than delaying it, so eastward trips take longer to recover from.

Does melatonin help?

Low-dose melatonin near the destination bedtime can help some travellers, especially eastward. Ask a doctor or pharmacist first, especially if you take other medicines.

Sources and further reading

Flight Time Calculator (Duration and Arrival Time)Enter the flight distance, departure time and time difference to estimate how long the… Time Zone ConverterFind out what time it will be somewhere else Sleep CalculatorGo to bed at a time that lets you wake at the end of a sleep cycle Distance Between Coordinates Calculator (Latitude and Longitude)Enter two sets of coordinates to get the straight-line distance over the Earth's… Baggage Size Calculator (Linear Inches and Weight)Enter your bag's dimensions and weight and your airline's limits to check if it fits

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