Free Jet Lag
Calculator

How to Use the Jet Lag Recovery Calculator

Start with the route, because recovery changes depending on whether you are advancing your body clock eastward or delaying it westward. A Frankfurt to Bangkok trip, a New York to London red-eye, and a Los Angeles to Tokyo flight can all feel different even when the flight time looks similar.

After you enter the flight details, use the result as a practical recovery plan rather than a strict medical schedule. The calculator gives you the best windows for sleep, bright light, dim light, meals, short naps, caffeine cutoffs, and optional melatonin timing so the first 24 to 72 hours at your destination are easier to manage.

This is a travel health planning tool, not a diagnosis. It helps you personalise your exposure to light, sleep schedule, and arrival-day routine around the way your internal body clock responds to travel across time zones.

Jet Lag Recovery Time: What to Expect

Jet lag occurs when your body's internal clock (circadian rhythm) is out of sync with the local time at your destination. The general rule is that it takes about one day to adjust for every time zone crossed when flying east, and roughly half to three quarters of a day per time zone when flying west.

Light Exposure

Light is the most powerful tool for resetting your internal clock. Our calculator suggests when to seek or avoid light based on your direction of travel. Morning light helps you wake up earlier (eastward travel), while evening light helps you stay awake longer (westward travel).

The awkward part is that exposure to light at the wrong time can do the opposite of what you want. If you arrive in a new time zone and flood your eyes with bright light too early or too late, your body clock may shift in the wrong direction and make recovery drag into the second or third day.

Sleep, Meals, Caffeine, and Naps

Sleep timing works best when the rest of the day supports it. Move meals toward destination time as soon as practical, keep caffeine at least six hours away from your target bedtime, and use naps as a rescue tool rather than a second sleep block. If you need to nap on arrival day, keep it to 15 to 20 minutes and avoid late afternoon.

Pre-Flight Preparation

If you have two or three days before departure, shift your bedtime gradually in the direction of the destination. For eastward flights, go to bed and wake up a little earlier. For westward flights, delay bedtime and seek light later in the day. Even a 30 to 60 minute shift before takeoff can make the first night easier.

Additional Tips

• Stay Hydrated: Drink plenty of water before, during, and after your flight.
• Avoid Alcohol: Alcohol disrupts sleep quality and worsens dehydration.
• Adjust Meals: Start eating meals at destination times a few days before travel.
• Consider Melatonin: Our calculator can suggest optimal timing for melatonin supplements.

Frequently Asked Questions

How long does jet lag usually last?

Jet lag often lasts about one day per time zone when flying east and about half to three quarters of a day per time zone when flying west. The calculator adjusts that estimate based on route direction and practical recovery habits.

Is eastward jet lag worse than westward jet lag?

Eastward travel is usually harder because your body has to fall asleep and wake earlier than it wants to. Westward travel is often easier because most people find it simpler to stay awake later.

What is the best light exposure for jet lag?

For eastward travel, morning light at the destination helps advance your body clock. For westward travel, late-afternoon or early-evening light helps delay it. Mistimed bright light can slow recovery.

Is jet lag worse on day 2?

It can be. Day 1 is often powered by adrenaline, airport movement, and the novelty of arrival. Day 2 is when fragmented sleep, early waking, and the mismatch between local time and your body clock can feel more obvious.

What are 5 symptoms of jet lag?

The five symptoms I would watch for are broken sleep, daytime fatigue, brain fog, digestive discomfort, and feeling disoriented at normal local hours. If symptoms feel severe or unusual, treat it as a travel health issue and speak with a qualified clinician.

How many hours is classed as jet lag?

Jet lag usually starts to become noticeable after crossing three or more time zones. A one or two hour shift can still make you tired, but that is often travel fatigue rather than true circadian jet lag.

Should meals follow home time or destination time?

For most trips, meals should move to destination time on arrival because food timing helps anchor your day. For very short trips, partial adjustment may be more realistic.