Jet Lag Adjustment Calculator
Recovery days and a light-exposure plan from time zones crossed and direction — circadian science, packaged.
Eastward hurts more because the internal clock runs naturally slightly *longer* than 24 h — delaying (west) goes with the grain, advancing (east) against it. Light is the master lever and mistimed light actively worsens it: after a big eastward hop, dawn light hits your body's subjective night and shifts you the wrong way — hence the avoid-morning-light rule for the first days after 8+ zones.
Formula
For general information only — not medical advice, a diagnosis or a treatment plan. Consult a qualified healthcare professional before making health, diet, medication or exercise decisions.
Recovery days and a light-exposure plan from time zones crossed and direction — circadian science, packaged. The Jet Lag Adjustment Calculator is a free, private jet lag calculator tool — every result computes instantly in your browser with no sign-up and no data upload.
About Jet Lag Adjustment Calculator
Eastward hurts more because the internal clock runs naturally slightly *longer* than 24 h — delaying (west) goes with the grain, advancing (east) against it. It applies body clock shifts ~1 h/day eastward, ~1.5 h/day westward. Use the Jet Lag Adjustment Calculator to get an instant, clearly-explained result with the working shown step by step — free, private and with the source method cited.
How to use Jet Lag Adjustment Calculator
- 1Enter your details in the Jet Lag Adjustment Calculator input fields above.
- 2The result updates instantly with the working and reference bands shown.
- 3Adjust any value to explore how it changes the outcome — it's free and unlimited.
Why use Jet Lag Adjustment Calculator?
- ✓Instant jet lag calculator result that recomputes as you type — no waiting, no page reloads
- ✓100% client-side: your health data never leaves your browser
- ✓Shows the actual formula and your numbers substituted in, so you can see exactly how the result is reached
- ✓Based on published, citable sources (Waterhouse J et al., Lancet 2007 — jet lag: trends and coping strategies)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Jet Lag Adjustment Calculator work?+
Eastward hurts more because the internal clock runs naturally slightly *longer* than 24 h — delaying (west) goes with the grain, advancing (east) against it. The calculation uses the formula: body clock shifts ~1 h/day eastward, ~1.5 h/day westward. Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Jet Lag Adjustment Calculator accurate, and what is it based on?+
The method is traceable to authoritative sources, including Waterhouse J et al., Lancet 2007 — jet lag: trends and coping strategies; Eastman CI & Burgess HJ, Sleep Med Clin 2009 — how to travel the world without jet lag. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Jet Lag Adjustment Calculator free and private?+
Yes. It's completely free with no sign-up, and all computation happens locally in your browser, so none of your health data ever leaves your device.
Can I use this for medical decisions?+
This tool is for general information only and is not medical advice. Always consult a qualified healthcare professional before making health decisions.
What can I use the Jet Lag Adjustment Calculator for?+
It's commonly used for jet lag calculator, time zone adjustment, jet lag recovery. Recovery days and a light-exposure plan from time zones crossed and direction — circadian science, packaged.
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