Human circadian rhythms drift slightly longer than 24 hours
That is one reason delaying sleep often feels easier than advancing it after eastbound travel.
Body clock
Jet Lag Recovery Planner
Calculator
Results
Ready to calculate
Use the controls on the left and calculate to see your result, units, and interpretation.
Use the controls on the left and calculate to see your result, units, and interpretation.
About This Tool
Crossing time zones is not just a travel logistics problem. It is a body-clock problem. A simple timezone converter tells you what time it is after landing, but it does not tell you how quickly your sleep schedule is likely to adapt or how to space that transition over the first few days of a trip. That is the gap this Jet Lag Recovery Planner is designed to fill. It turns an origin timezone, destination timezone, arrival date, and your usual sleep window into a practical adjustment plan you can follow before and after travel.
The planner estimates your clock shift by comparing the origin and destination timezone offsets on the selected travel date. That matters because daylight saving rules change over the year and can alter the real adjustment required by an hour or more. Once the tool knows the effective offset, it calculates the number of days needed to adapt at the pace you choose. Many travellers can comfortably shift around one hour per day, but some prefer a slower, gentler plan for longer trips. The tool works entirely in your browser, so itineraries and sleep preferences stay private.
The output is intentionally practical. You get the headline number of recovery days, whether the trip is eastbound or westbound, and a day-by-day bedtime and wake-time schedule. Eastbound travel is usually harder because it asks you to fall asleep earlier; westbound travel often feels easier because it resembles a later bedtime. The planner reflects that reality in its interpretation text, but it still leaves the pace in your control. That makes it useful for leisure trips, business travel, flight crews, conferences, and frequent flyers who need to manage alertness before important meetings.
This tool is also a planning aid rather than a medical tool. It does not diagnose sleep disorders or account for medications, light therapy devices, or unusual work rosters. What it does provide is a clean, timezone-aware framework for sleep timing decisions. Used alongside your existing route and schedule planning, it gives you a more realistic idea of when you will feel aligned with the local clock and when you may still be working against it.
Formula
timezone difference = destination offset − origin offsetestimated recovery days = ceil(abs(timezone difference) / daily adjustment pace)daily sleep shift = timezone difference / recovery days
Example Calculation
Example: if you normally sleep from 23:00 to 07:00 in New York and arrive in Paris on a date when the effective clock difference is 6 hours eastbound, using a pace of 1 hour per day gives an estimated recovery window of 6 days. The planner then shifts your bedtime and wake time roughly one hour earlier each day until they match the destination schedule.
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FAQs
How does the planner estimate recovery time?
It compares the origin and destination timezone offsets for the selected travel date, then divides the clock shift by your chosen daily adjustment pace.
Why are eastbound trips usually harder?
Eastbound travel asks most people to fall asleep earlier than their usual body-clock preference, so the plan typically recommends more deliberate light and bedtime changes.
Does this tool use external travel data?
No. Everything runs client-side in your browser using built-in timezone rules, with no external APIs or uploaded itinerary data.
Can I use it for a short business trip?
Yes. The recovery estimate helps even on short trips because you can decide whether to fully adjust or only partially shift for the stay length.
Is this medical advice?
No. It is a planning tool based on clock differences and gradual sleep shifts, not individualized medical guidance.
5 Facts
Cabin light exposure matters
Even without crossing more time zones, poorly timed light can reinforce the wrong local schedule after arrival.
Travel habits
Performance dips often appear on day two
The first day can feel manageable on adrenaline, while the deeper sleep-pressure mismatch shows up after the first local night.
Recovery pattern
Meal timing is a useful cue
Regular meals at destination times help reinforce your new schedule alongside light and sleep timing.
Routine design
Short-haul trips still create social jet lag
Even a modest shift can disrupt meetings and alertness if it lands against your habitual bedtime.
Business travel
Important Note
This planner is informational only. If you have a diagnosed sleep condition, take medication affecting alertness, or need medical clearance for travel, use this output only as a scheduling reference and speak to a qualified clinician for personalized advice.