SoloSquareBefore you go
Give your sleep and light a gentle head start, with up to three days of preparation.
FREE JET LAG PLANNER
London to
Sydney.
A little preparation.
More of your first day.
A practical plan for sleep, light and crossing time zones.
Made around your flights, any connections and your usual rhythm.
About a minute No sign-up Free for every trip
YOUR NEXT JOURNEY
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LESS GUESSWORK, MORE POSSIBILITY
A rhythm for the journey.
On the way
Rest on each flight, light timed by a body-clock model, and calm guidance at every connection and once you land.
Keep it close
Save the plan for the plane, put it in your calendar, or print a copy for your bag.
YOUR ROUTE, EXPLAINED
Opposite seasons, a large clock shift
These cities change their clocks in opposite seasons. Large shifts make body-clock estimates less reliable; the tool deliberately leaves out precise light timing for shifts of eight hours or more.
The table shows Sydney relative to London on the 15th of each month in 2027. Clock changes can happen within a month: enter your exact dates above for your trip.
- London
- Europe/London
- Sydney
- Australia/Sydney
Plan an easy first day, leave time to rest and avoid driving when sleepy. A saved schedule is a reminder, not a requirement to ignore how you feel.
Explore the Sydney guideJanuary11h ahead
February11h ahead
March11h ahead
April9h ahead
May9h ahead
June9h ahead
July9h ahead
August9h ahead
September9h ahead
October10h ahead
November11h ahead
December11h ahead
Informed by sleep science.
Honest about the limits.
Light is the body clock's strongest cue. Your light windows come from a published mathematical model of the human body clock, simulated with your flights and sleep. It is an independent planner, not clinically validated, and anonymous check-ins after trips help us learn how well it works.
Read the method, sources and limitationsBy the SoloSquare team · Method v2.0.0 · Reviewed 18 October 2026
START WITH YOUR ROUTE
Different time zones.
Different first days.
GOOD TO KNOW
A few things
before you fly.
What does a jet lag calculator do?
It turns your route, travel dates and usual sleep times into a planning schedule. This free tool times light with a published model of the human body clock and shows preparation, rest during travel and up to five days after arrival. It does not measure your circadian rhythm or promise to prevent jet lag.
Does traveling east or west make a difference?
Usually. Moving your sleep earlier is often harder than moving it later. On date-line routes, the shorter clock adjustment can differ from the flight's compass direction. Your plan shows the actual clock difference separately from that adjustment.
Does it work with connecting flights?
Yes. Choose With stops and add up to three connections, using the local landing and take-off times on your ticket. Each flight gets its own rest windows, and each connection shows the time there and whether it is night on your destination clock. Stopovers of 24 hours or more need a separate plan.
What about melatonin?
A Cochrane review found that melatonin reduced jet lag after flights across five or more time zones, especially eastward. This planner does not recommend medication, supplements or doses: timing, health conditions, interactions and local rules matter. Ask a doctor or pharmacist first. See the CDC guidance and NHS advice.
Is this a free alternative to Timeshifter?
It is an independent, free browser planner. Timeshifter offers a more extensive app with its own proprietary model and notifications. SoloSquare times light with a published academic model of the human body clock (Forger, Jewett & Kronauer, 1999). We are not affiliated with Timeshifter and have not established comparable effectiveness.
Does it really work?
Timed light is one of the best-studied ways to shift the body clock, and the planner follows a published model of it. This planner itself has not been tested in a clinical trial, so we do not quote a success rate. After your trip, a 30-second anonymous check-in tells us how it went, and we use the answers to measure and improve it.
Can I use my plan on the plane?
Yes. After building it, choose Save offline for a self-contained file, or Add to calendar for an .ics file. Open the saved file before your trip to check it works on your device. Building or rebuilding a plan needs an internet connection; there are no push reminders.
What happens to my flight details?
They are sent to SoloSquare to calculate the plan and are not saved in a member profile or a trip database. These tool pages load no analytics or ad pixels. Saving a file keeps a copy on your device; sharing a plan link puts the itinerary in the link's fragment, so only share it with people you choose.
WHEN YOU’RE READY TO EXPLORE
A new city.
A little good company.
Meet solo travelers and locals over something simple.