Jet Lag Recovery Calculator
Estimate how many days it will take to recover from jet lag based on the number of time zones crossed.
How to use this tool
- Enter the number of time zones your flight crosses.
- Select whether you are flying east or west — eastbound travel is generally harder to recover from.
- The calculator estimates recovery days based on the commonly used 1.5 days per time zone rule.
Find out how long your body needs to adjust after crossing multiple time zones.
⚠ This tool is for general information and education only and is not medical advice. Consult a qualified healthcare professional before making health decisions.
Formula
Base recovery (days) = time zones crossed ÷ 1.5
Direction multiplier: 1.2 if travelling east, 1.0 if travelling west
Recovery days = round(base × multiplier, 1)
How it works
This calculator estimates jet-lag recovery time by dividing the number of time zones crossed by 1.5 — a commonly cited rule of thumb reflecting the body's ability to shift its circadian rhythm by roughly 1–1.5 hours per day. Eastward travel is penalised by a 20% multiplier because advancing the body clock is physiologically harder than delaying it. The result is rounded to one decimal place and is an approximation; individual recovery varies with age, sleep quality, and light exposure.
Worked example
- Time zones crossed = 6, direction = west
- Base recovery = 6 ÷ 1.5 = 4.0 days
- Direction multiplier for westward travel = 1.0
- Recovery days = round(4.0 × 1.0, 1) = 4.0 days
Estimated recovery time = 4.0 days
Common mistakes to avoid
- Counting the total time zones on a world map rather than the net time-zone shift. Flying from New York to Los Angeles crosses 3 time zones westward regardless of the route shown.
- Applying the eastward multiplier (1.2x) to westward travel. The body adapts more easily going west (extending the day) than east (shortening the day); the direction must match actual travel direction.
- Treating the estimate as a hard recovery deadline. The 1-day-per-1.5-time-zones rule is a population average; individual recovery depends on sleep quality, light exposure, and melatonin use.
Key terms
- Jet lag
- Temporary disruption of the body's internal clock caused by rapid travel across multiple time zones, leading to fatigue, insomnia, and poor concentration.
- Circadian rhythm
- The roughly 24-hour internal biological cycle that governs sleep, wakefulness, appetite, and hormone levels.
- Phase advance (eastward)
- Shifting the body clock earlier, required when travelling east; generally harder to achieve than a phase delay.
- Phase delay (westward)
- Shifting the body clock later, required when travelling west; the body adapts more easily to this direction.
- Melatonin
- A hormone produced by the pineal gland that signals darkness and sleep; often used as a supplement to help reset the circadian rhythm after long-haul flights.
Frequently asked questions
- How long does jet lag last?
- A common rule of thumb is one day of recovery per 1.5 time zones crossed. Eastbound travel is usually harder; westbound travel allows the body to extend its natural day.
- How can I recover from jet lag faster?
- Adjust your sleep schedule before departure, stay hydrated, avoid alcohol on the flight, get natural daylight at the destination, and try melatonin if recommended by your doctor.