Jet Lag Calculator
This jet lag calculator estimates how badly a trip will throw off your body clock and builds a personalized, day-by-day adjustment schedule for you. Enter your departure and arrival locations plus your usual sleep times, and it predicts your recovery in days and tells you exactly when to seek light, sleep, and cut off caffeine.
It is for anyone crossing time zones — frequent flyers, holiday travelers, and athletes or business travelers who need to land sharp. Instead of generic "drink water, get sunlight" advice, you get specific clock times tuned to your route and your travel direction.
How to Use the Jet Lag Calculator
Pick your time zones
Open the Departure and Arrival dropdowns and search by country. Countries with several zones expand into a city list with UTC offsets — choose the closest one. Your departure zone is auto-detected from your browser, and the Swap button reverses the route in one click.
Set your sleep schedule
Enter your normal Bedtime and Wake Time (defaults are 11:00 PM and 7:00 AM). Accurate times produce a more precise plan.
Calculate
Press Calculate Jet Lag. You get an assessment (zones crossed, direction, estimated recovery days, severity), a day-by-day adjustment schedule, and direction-specific tips. Once calculated, the plan updates instantly when you change any input.
Read the schedule
Pre-trip days show times in Home Time; the travel day and recovery days show Destination Time. Each day lists when to seek light, when to avoid it, your sleep window, and a caffeine cutoff.
Features
Country-Based Time Zone Selection
Search countries by name with national flags. Single-zone countries select instantly; multi-zone countries expand to a city list with each city's UTC offset.
Auto-Detected Departure
Your starting time zone is detected from your browser the moment the tool loads, so you only have to choose your destination.
Severity Assessment
Your jet lag is rated Mild (1-3 zones), Moderate (4-7 zones), or Severe (8+ zones), with an estimated recovery time in days.
Day-by-Day Schedule
A plan that spans pre-trip preparation days and post-arrival recovery days, with each day broken into clear, actionable time blocks.
Light Exposure Windows
Each day tells you exactly when to seek bright light and when to avoid it — the most powerful lever for resetting your body clock.
Recommended Sleep Times
A target bedtime and wake time for every day of the plan, gradually shifting toward your destination schedule.
Caffeine Cutoffs
A daily "no caffeine after" time so a late coffee never sabotages the sleep your body is trying to reset.
Direction-Aware Advice
Eastward and westward trips need opposite strategies. Light, sleep, and tip recommendations flip automatically based on your travel direction.
One-Click Swap
Reverse departure and arrival with the swap button to plan your return trip without re-entering anything.
Custom Sleep Times
Set your own bedtime and wake time so the entire schedule is built around your real sleep pattern, not a generic default.
Tips for Beating Jet Lag
Start Before You Fly
Begin shifting your sleep 1-2 days early. Even a small pre-trip shift in the right direction lowers the severity you arrive with.
Use Light Strategically
Get bright morning light when flying east to advance your clock; get evening light when flying west to delay it.
Hydrate, Skip the Booze
Stay well hydrated on the flight and go easy on alcohol and excess caffeine — both worsen disrupted sleep.
Keep Naps Short
If you must nap, limit it to 20-30 minutes before 3 PM local time so it does not steal from night sleep.
Frequently Asked Questions
How long does jet lag last?
It depends on how many time zones you cross and which direction you fly. As a rule of thumb, the body adjusts about 1 zone per day flying east and roughly 1.5 zones per day flying west. The calculator turns your specific route into an estimated recovery time in days.
How many days does it take to recover per time zone?
Eastward travel recovers at about one day per time zone, while westward travel is faster because delaying your clock is easier than advancing it. The calculator applies these rates to your zones crossed and shows the estimate as "~N Days" in the assessment.
Is jet lag worse flying east or west?
Eastward travel is usually harder. Your internal clock naturally runs slightly longer than 24 hours, so it is easier to stay up later (west) than to fall asleep earlier (east). That is why the plan recommends different strategies for each direction.
When should I take melatonin for jet lag?
For eastward trips, the tips suggest considering a low dose of melatonin (0.5-3 mg) about 30 minutes before your target bedtime to help advance your clock. Melatonin affects people differently, so check with a healthcare professional before using it.
What does "seek bright light" mean?
Bright light is the strongest signal for resetting your body clock. During the recommended window, spend time outdoors in natural sunlight or use a bright artificial light. Even 30-60 minutes of exposure makes a meaningful difference.
What does "avoid bright light" mean?
During that window, minimize sunlight and bright screens — wear sunglasses outdoors, dim indoor lights, and lower screen brightness. This keeps your body clock from shifting in the wrong direction.
Should I start adjusting before my trip?
Yes. The schedule includes pre-trip days that nudge your sleep time 1-2 days before departure. Even a small early shift reduces how severe your jet lag feels on arrival.
Does the calculator account for daylight saving time?
Yes. Time zone offsets are read in real time from your browser's built-in internationalization data, which reflects each zone's current daylight saving status automatically.
What if my country has multiple time zones?
When you pick a country with several zones, the dropdown expands into a city list. Choose the city closest to your departure or arrival point for the most accurate calculation.
How accurate is the recovery estimate?
The estimate is based on established circadian-rhythm rates. Real recovery varies with age, health, light habits, and how closely you follow the plan, but most people land within 1-2 days of the predicted time. Treat it as guidance, not medical advice.
No comments yet. Be the first to comment!