Jet Lag Recovery Calculator
Estimate how long jet lag takes to clear, based on zones crossed and direction of travel.
Eastward is harder
The human circadian rhythm runs slightly longer than 24 hours, so stretching a day — flying west — is easier than compressing one. Flying east from London to Tokyo typically takes eight or nine days to clear; the same trip back takes five or six. Morning light helps after eastward travel, evening light after westward.
The formula
Roughly one day per time zone eastward, and about 1.5 zones per day westward
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Jet Lag Recovery Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
Jet Lag Recovery Calculator — frequently asked questions
Is this jet lag recovery calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 23, 2026 · Calculation runs client-side · No data collected · Report an error