A flight from London (LHR) to Bangkok (BKK) typically takes about 11 h 20 min. The return, Bangkok to London, takes about 13 h 5 min. The distance is 9,577 km (5,951 miles) along the great-circle path.
The jet stream, a fast river of air at cruising altitude, blows mostly from west to east. Flying London to Bangkok you ride it, about 11 h 20 min; flying Bangkok to London you fly into it, about 13 h 5 min. It is the same distance either way, which is why the westbound leg is usually the longer one.
Bangkok is 7 hours ahead of London (standard time; the gap shifts by an hour for part of the year when only one of them is on daylight saving). Leave London at 10:00 and you land at about 04:20 Bangkok time, the next day.
Bangkok is 7 hours ahead, so your body clock has to move earlier. That is the harder direction: with no plan, expect about 7 days to feel properly adjusted.
For two or three days before, go to bed and get up an hour earlier each day, and get bright light soon after waking. Even a partial shift helps.
Set your watch to Bangkok time as you board. On a typical morning departure you land around 04:20 Bangkok time, in the evening or at night: try to sleep on the flight, with an eye mask and earplugs, drink water, go easy on alcohol, and go to bed soon after you arrive.
Get outdoor light in the morning and avoid bright light in the evening for the first few days. Keep any nap under 30 minutes, and have caffeine only before noon.
General guidance, not medical advice. If you have a health condition or take medication, ask your doctor before changing your sleep routine.
Range decides what can do this route without a stop. At 9,577 km it is within reach of Boeing 787-9, Airbus A350-900 and Boeing 777-300ER.
| Aircraft | Approx. range | Estimated LHR–BKK |
|---|---|---|
| Airbus A320neo | 6,300 km | needs a stop |
| Boeing 737-800 | 5,400 km | needs a stop |
| Airbus A321LR | 7,400 km | needs a stop |
| Boeing 787-9 | 14,100 km | 10 h 30 min |
| Airbus A350-900 | 15,000 km | 10 h 30 min |
| Boeing 777-300ER | 13,650 km | 10 h 25 min |
Distance is the great-circle distance between London Heathrow and Bangkok Suvarnabhumi. Time is that distance at about 830 km/h cruise, adjusted for the prevailing jet stream, plus roughly 35 minutes for taxi, climb and descent. It is a typical scheduled-time estimate, not a timetable: airlines publish their own, and daily winds, routing and air traffic can move a long flight by half an hour or more. Reviewed October 2026.
About 11 h 20 min from LHR to BKK. The return flight is about 13 h 5 min.
From London to Bangkok it is typically about 11 h 20 min, covering 9,577 km.
9,577 km (5,951 miles, 5,171 nautical miles) in a straight line.
The jet stream blows west to east, so the eastbound flight is shorter than the westbound one. The distance is identical.
Bangkok is 7 hours ahead of London in standard time.
At 9,577 km it is within the range of long-haul airliners such as the Boeing 777-300ER, so a non-stop flight is possible; check airline schedules for what is actually operated.
Typically about 7 days with no plan, and less if you shift your sleep and light exposure to local time.
Shift your sleep an hour earlier for two or three days before you fly, switch to destination time on boarding, sleep on the flight when it is night there, and get outdoor light in the morning after you land.
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