Jet Lag Recovery Calculator

About the Jet Lag Recovery Calculator

Estimates how long it typically takes to adjust to a new time zone, using the rule of thumb of about one day per time zone crossed, with eastward travel being harder.

How to use

Enter the number of time zones crossed and direction, then click Calculate.

Worked example

6 zones eastward → about 6 to 7 days to fully adjust.

How to use this calculator

1. Count how many time zones you crossed on your trip.
2. Divide that number by 2 to estimate your adjustment time.
3. Read the result as an approximate number of days, then round if you want a simple planning number.

The formula explained

• \(\text{days to adjust}\) = the estimated number of days your body may need to adapt to the new time zone
• \(\text{time zones crossed}\) = the number of time zones you travel across
• \(2\) = the tool's adjustment rate, meaning about one day of recovery for every two time zones

Step by step method

1. Start with the total number of time zones crossed.
2. Use the calculator's formula to divide that number by 2.
3. Check the result and interpret it as an estimate, not an exact medical timeline.
4. Use the estimate to plan rest, sleep, and your first few days after arrival.

Worked example

Suppose you flew from New York to Paris and crossed 6 time zones.

1. Use the formula \(\text{days to adjust} = \frac{\text{time zones crossed}}{2}\).
2. Substitute the trip length: \(\frac{6}{2} = 3\).
3. The calculator gives an estimate of 3 days to adjust.

Tips and common mistakes

• Count the time zones crossed, not the number of flight hours.
• The result is an estimate, so your actual recovery can be shorter or longer.
• Large westward and eastward trips can feel different, even with the same time zone count.
• If you want a simple planning number, round to the nearest whole day.

Frequently asked questions