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.
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
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
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.