🕐 Jet Lag Calculator

This jet lag calculator compares your departure and arrival time zones to estimate how many zones you're crossing, whether you're traveling eastward or westward, and roughly how many days it may take your body clock to adjust. It's built for travelers who want a quick, practical estimate before a long-haul flight rather than a vague "you'll probably feel jet lagged" warning.

How It Works

The calculator finds the current UTC offset of both your departure and arrival time zones and takes the difference to determine the number of zones crossed and the direction of travel. Eastward travel (arrival zone ahead of departure zone) is estimated at roughly one recovery day per time zone crossed, since it requires falling asleep earlier than your body naturally wants to. Westward travel is estimated at about one recovery day per 1.5 time zones crossed, since lengthening your day by staying up later is generally easier for the body's circadian rhythm to handle.

Why It Matters

Jet lag affects sleep, digestion, mood, and mental sharpness, and can meaningfully impact the first few days of a trip — whether for a vacation, an important meeting, or a competition. Knowing roughly how many days to budget for adjustment, and which direction-specific habits actually help, lets you plan a more realistic itinerary instead of scheduling demanding activities right after landing.

Tips for Accurate Results

• Recovery time estimates are a general rule of thumb — individual factors like age, sleep quality, and flight timing also affect how quickly you adjust.
• Crossing 1–2 time zones typically causes minimal jet lag for most travelers, even though the calculator still reports a direction.
• Combine this with the Flight Time Calculator to see your total time zones crossed on multi-leg trips with layovers.
• Start adjusting your sleep schedule a few days before departure, in the direction suggested by the eastward or westward tips below.