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Jet Lag Calculator

Estimated recovery days based on time zones crossed and travel direction.

Introduction

Jet Lag Calculator — Estimated recovery days based on time zones crossed and travel direction. Enter Origin UTC offset (hours), Destination UTC offset (hours), Direction of travel to get an instant, accurate result.

Formula

A commonly published rule-of-thumb estimate, not a medical formula: recovery days ≈ (number of time zones crossed) × a direction factor. Eastward travel uses 1.5 days per zone (circadian research shows it's generally harder to adjust to, since it requires advancing your body clock); westward travel uses 1.0 day per zone (delaying your body clock is typically easier).

Step-by-step

  1. Enter the Origin UTC offset (hours).
  2. Enter the Destination UTC offset (hours).
  3. Enter the Direction of travel.
  4. Click Calculate to see your result instantly.

Real-world example

Example: With Origin UTC offset (hours) = -5, Destination UTC offset (hours) = 1, Direction of travel = eastward, the Jet Lag Calculator gives Timezone Diff: 6, Direction: eastward, Recovery Days Estimate: 9.

Frequently Asked Questions

Why does eastward travel get a higher recovery estimate?
Flying east requires your body clock to shift forward (go to bed/wake up earlier), which most circadian research finds harder to adapt to than the backward shift needed flying west — this calculator reflects that with a higher per-zone factor.
Is this an exact prediction of how long I'll feel jet-lagged?
No — it's a widely used rule-of-thumb estimate. Actual recovery varies by individual, sleep quality, light exposure, and how many zones you cross, so treat the result as a rough guide rather than a guarantee.
How do I find my UTC offset?
Search "[city] UTC offset" or check your phone's world clock — enter it as a positive or negative number of hours from UTC.
What inputs does the Jet Lag Calculator need?
You'll need to provide: Origin UTC offset (hours), Destination UTC offset (hours), Direction of travel. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Jet Lag Calculator?
The Jet Lag Calculator applies the formula exactly as calculated — A commonly published rule-of-thumb estimate, not a medical formula: recovery days ≈ (number of time zones crossed) × a direction factor. Eastward travel uses 1.5 days per zone (circadian research shows it's generally harder to adjust to, since it requires advancing your body clock); westward travel uses 1.0 day per zone (delaying your body clock is typically easier). — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Jet Lag Calculator free to use?
Yes, the Jet Lag Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Jet Lag Calculator

The Jet Lag Calculator uses a real, verifiable formula — A commonly published rule-of-thumb estimate, not a medical formula: recovery days ≈ (number of time zones crossed) × a direction factor. Eastward travel uses 1.5 days per zone (circadian research shows it's generally harder to adjust to, since it requires advancing your body clock); westward travel uses 1.0 day per zone (delaying your body clock is typically easier). — so results are accurate every time, not an approximation.