Why Yokohama is always 2 hours ahead of Bangkok
Yokohama runs on Japan Standard Time (JST), which is UTC+9. Bangkok runs on Indochina Time (ICT), which is UTC+7. The math is simple: Yokohama is always 2 hours ahead.
When it's 8:00 AM in Bangkok, it's 10:00 AM in Yokohama. When it's 6:00 PM in Yokohama, it's 4:00 PM in Bangkok. No adjustments for "spring forward" or "fall back" are needed, because neither Japan nor Thailand observes daylight saving time. This makes scheduling between the two cities straightforward year-round.
What does the 2-hour gap look like across a working day?
| Event | Bangkok (ICT, UTC+7) | Yokohama (JST, UTC+9) |
|---|---|---|
| Start of workday | 9:00 AM | 11:00 AM |
| Lunch break | 12:00 PM | 2:00 PM |
| End of workday | 5:00 PM | 7:00 PM |
| Evening dinner | 7:00 PM | 9:00 PM |
The 2-hour gap means that the entire standard business day overlaps. A 9:00 AM start in Bangkok is a comfortable 11:00 AM in Yokohama, late enough that no one is rushing to a first-thing call. A 5:00 PM end in Bangkok is 7:00 PM in Yokohama, which is after typical office hours but still within a reasonable window for a short call.
When is the best time to call between Bangkok and Yokohama?
The overlap is generous. The best window for calls and meetings is from 9:00 AM to 3:00 PM Bangkok time, which corresponds to 11:00 AM to 5:00 PM Yokohama time. That covers the core of both workdays.
The sweet spot is 10:00 AM Bangkok / 12:00 PM Yokohama. Both sides are settled into their morning routines but not yet into afternoon slumps.
If you are in Bangkok and need to catch someone in Yokohama before they leave for the day, your last reliable call time is 3:00 PM Bangkok time (5:00 PM Yokohama). If you are in Yokohama and need to catch someone in Bangkok at the start of their day, your first reliable call time is 10:00 AM Yokohama time (8:00 AM Bangkok).
What happens to your body clock on a Bangkok, Yokohama flight?
A direct flight from Narita (Tokyo) to Bangkok takes about 6 to 7 hours. A direct flight from Bangkok to Narita takes about 5.5 to 6.5 hours, thanks to the jet stream.
Because Yokohama is ahead, flying from Bangkok to Yokohama means you "lose" 2 hours on the clock. A flight departing Bangkok at 9:00 AM and arriving in Tokyo at 4:00 PM local time feels like a 7-hour trip, but your body only adjusted to a 2-hour shift. Jet lag is usually mild.
Flying the other way, from Yokohama to Bangkok, you "gain" 2 hours. A 9:00 AM departure from Tokyo arrives in Bangkok at 12:00 PM local time. That afternoon arrival gives you time to check in and have a late lunch.
No DST changes mean your flight schedule won't be disrupted by a clock change in either city. The next change that affects your planning is the shift to summer schedules at some airlines, which typically happens in late March. Check with your carrier for exact dates.