Circadian Calculator

Online Jet Lag Calculator & Recovery Estimator

Estimate your recovery timeline, clock shifts, and time zones crossed. Enter your flight itinerary below to diagnose your jet lag risks.

Free Preview Builder

See what jet lag will try to steal from your trip.

The free preview diagnoses your trip risks; upgrading unlocks full calendar files, custom timing, Google Calendar sync, and replans.

Flight segments1/10 included in this trip
Flight 1
Sleep profileYour traveler profile and baseline sleep habits
⚙️ Schedule Alerts & TuningExpand options ▼

How does the Jet Lag Calculation work?

Traditional jet lag calculators only count the number of time zones you cross and recommend a generic "one day of recovery per time zone" rule. While that is a simple rule of thumb, it ignores the critical biology of your body clock (your circadian rhythm).

Arrive Ready's jet lag risk estimator calculates a customized Jetlag Risk Score out of 100 using several biological and flight factors:

  • Direction of travel (Clock Shift): Traveling east (advancing your clock) is scientifically harder to adjust to than traveling west (delaying your clock). We apply heavier adjustments for eastbound routes.
  • Flight timing & arrival window: Landing between 5 AM and 10 AM (local time) forces you to stay awake on high sleep debt, creating a severe sleep deficit.
  • Total cabin airtime: Long flights cause physical fatigue and dehydration, which exacerbate the cognitive symptoms of jet lag.
  • Your personal sleep habits: Your usual bedtime, wake time, and how easily you sleep on a plane modify how your body clock shifts.

Maximizing Your Circadian Recovery

Overcoming jet lag is not about sleeping as much as possible; it is about exposing your eyes to light at the correct biological times.

  1. Timed Light Exposure: Light is the primary cue (zeitgeber) that resets your brain clock. Getting light at the wrong time can actually shift your clock in the wrong direction, making your jet lag worse.
  2. Strategic Melatonin: Melatonin acts as a darkness signal. Taken at the correct circadian phase, it helps advance or delay your body clock to match your destination.
  3. Caffeine Cutoffs: Caffeine is useful for staying alert, but using it too late blockades adenosine receptors and prevents you from falling asleep when your plan requires it.

Unlock Your Full Calendar-Sync Plan

Once you compute your risk preview, you can unlock a personalized, step-by-step circadian schedule. Your paid plan syncs directly with your Google Calendar, iOS Calendar, or Outlook to keep your plan with you offline.