Jet Lag Calculator
Tell it how many zones you're jumping and which way, and it gives you a ballpark for how long you'll feel foggy — plus a few things that genuinely help you land ready.
Estimate your jet lag recovery
A rough rule of thumb: your body clock shifts about an hour a day, and flying east is harder than flying west. Tell it how far you're jumping and which way.
Rough recovery time
5 days
A ballpark, not a promise
Direction
Eastbound
Crossing 6 zones heading east, plan on roughly 5 days to feel like yourself again.
- •Eastbound is the tough one — you're losing hours, so start shifting to an earlier bedtime a few days out.
- •Grab morning light at your destination to pull your clock forward.
- •Skip long naps; push through to a local-time bedtime.
- •Consider melatonin in the early evening (check with a doctor first).
The rough science of jet lag
Your internal clock runs on roughly a 24-hour cycle, and it doesn't jump zones as fast as a plane does. Land somewhere six hours off and your body is still keeping the old schedule — hungry at the wrong times, wide awake at 3 a.m.
The clock resets about an hour a day, which is where the day-per-zone rule comes from. Flying east makes it harder because you're asking your body to sleep before it's ready; flying west is gentler because staying up late is easy for most of us.
None of this is exact. Your age, how you slept on the plane, and how well you time your light all move the needle. Use the estimate to plan a low-key first day rather than scheduling a big meeting the morning you land.
Frequently asked questions
Why is flying east worse than flying west?
Heading east you lose hours and have to fall asleep earlier than your body wants, which it resists. Westbound you gain hours and just stay up a little later, something most people manage without much fuss. That's why the estimate runs longer for eastbound trips.
How is the recovery estimate calculated?
It starts from the old rule that your body clock shifts about an hour a day, then adjusts down a bit for the easier westbound direction. Cross six zones eastbound and it lands around five to six days; the same trip west comes out shorter.
Do short hops cause jet lag?
Rarely. Under three time zones your body usually shrugs it off within a day, so the tool tells you as much rather than inventing a recovery period. A one- or two-hour shift is more 'slightly off' than true jet lag.
Does daylight really help?
It's one of the strongest levers you have. Morning light after an eastbound flight nudges your clock earlier, and evening light after flying west pushes it later. Timing your sunlight is often more effective than any supplement.
Is this a substitute for medical advice?
No — it's a rough planning aid, not a health service. If you rely on medication timing, have a sleep disorder, or are considering melatonin, talk to a doctor. Bodies vary, and the number here is just a ballpark to plan a light first day around.
How can I beat jet lag faster?
Start shifting your sleep a day or two before you fly, chase the right light at your destination, stay hydrated, and get onto local meal and sleep times as soon as you land. It won't erase the lag, but it usually shortens it.