How to Find Overlapping Business Hours
Hong Kong Standard Time (HKT, UTC+8) does not move. No daylight saving, no seasonal clock change. Every other city shifts around it.
That is the only rule you need. Once you know Hong Kong’s offset stays fixed, the scheduling problem becomes a question of when the other city changes its clocks.
Standard office hours in Hong Kong run 09:00-18:00 HKT, Monday to Friday. Lunch is typically 12:30-14:00. The best overlap windows below use a 09:00-17:00 workday in the other city unless noted otherwise.
Hong Kong + London + New York: The Three-City Challenge
The overlap: 15:00-16:00 HKT.
This is the hardest trio to schedule. It works because of the way the time differences stack.
On 15 January 2026, London is 8 hours behind Hong Kong, and New York is 13 hours behind. At 15:00 HKT, London is at 07:00 GMT. New York is at 02:00 EST, still asleep. The reverse happens later: by 21:00 HKT, New York is at 08:00 EST, but London is at 13:00 GMT and Hong Kong’s business day is over.
The 15:00-16:00 HKT slot sits right at the point where London is open (08:00-09:00 GMT) and New York is waking up (02:00-03:00 EST). New York won’t be at their desks, but they can join a pre-market briefing. Many New York traders and bankers are already checking screens by 07:00 EST, and 02:00-03:00 EST is 07:00-08:00 in New York.
In July, the window shifts. On 15 July 2026, London is 7 hours behind (BST), and New York is 12 hours behind (EDT). At 15:00 HKT, London is 08:00 BST, New York is 03:00 EDT. The same logic applies: London is fully open, New York is pre-market.
Why a lunch-hour overlap does not exist
People try to fit all three into a “lunch hour” overlap. It does not exist. The 15:00-16:00 HKT slot is the only viable window. If you need all three cities live, book it there.
When to skip New York from the call
If New York attendance is non-negotiable and you need them fully at their desks, drop London. Run the call at 21:00 HKT. New York gets 08:00 EST. London is at 13:00 GMT, which is still workable but not ideal.
What to do in summer months
The window tightens. Book 15:00 HKT sharp. By 16:00 HKT, London is at 09:00 BST and heading into meetings. New York is at 04:00 EDT. The later you push, the worse it gets for New York.
Hong Kong + Singapore + Tokyo: Easy Asia-Pacific Calls
The overlap: full business day.
Singapore is on Singapore Standard Time (UTC+8) year-round, same as Hong Kong. There is zero time difference. Tokyo is on Japan Standard Time (UTC+9), 1 hour ahead of Hong Kong.
That means 09:00 HKT is 09:00 in Singapore and 10:00 in Tokyo. 17:00 HKT is 17:00 in Singapore and 18:00 in Tokyo. Every hour of the Hong Kong business day overlaps with both cities.
The only scheduling risk
Tokyo finishes lunch earlier than Hong Kong. Tokyo lunch is typically 12:00-13:00 JST, which is 11:00-12:00 HKT. If you book a 12:30 HKT call, Tokyo is at 13:30 JST and back from lunch. Fine.
Best time to book
Aim for 10:00 HKT. Singapore is at 10:00, Tokyo at 11:00. Everyone is settled in, no lunch conflicts, and you avoid the late-afternoon energy dip.
What to skip
Do not overthink this one. Any slot between 09:00 and 17:00 HKT works. The only mistake is booking before 09:00 HKT, which puts Tokyo before 10:00 JST.
Hong Kong + Dubai + Europe: The Middle East Bridge
The overlap: 13:00-16:00 HKT.
Dubai is 4 hours behind Hong Kong year-round. Dubai does not observe daylight saving time either. On 15 January 2026, 13:00 HKT is 09:00 GST in Dubai. 16:00 HKT is 12:00 GST, mid-morning for Dubai.
This window also works for Europe. At 13:00 HKT, Paris is 06:00 CET (winter) or 07:00 CEST (summer). At 16:00 HKT, Paris is 09:00 CET or 10:00 CEST. You get a 3-hour overlap where Dubai is fully open and Europe is entering its morning.
Why 13:00 HKT is the hard floor
Booking before 13:00 HKT risks an empty Dubai conference room. At 12:00 HKT, Dubai is 08:00 GST. Many Dubai offices start at 09:00 GST, so 13:00 HKT (09:00 GST) is the safe earliest time.
Which European cities to prioritise
Paris is 7 hours behind in January, 6 hours behind in July. London is 8 hours behind in January, 7 hours behind in July. If you need both Dubai and a European city, anchor the time to Dubai’s 09:00 GST start and let the European city join when it can.
What to skip
Do not book a 16:30 HKT call expecting full European participation. Paris is at 09:30 CET or 10:30 CEST, which is fine. But Dubai is at 12:30 GST, approaching lunch. The window closes at 16:00 HKT.
Hong Kong + Sydney + Auckland: Oceania Alignment
The overlap: 09:00-14:00 HKT.
Sydney is 3 hours ahead of Hong Kong in January (AEDT) and 2 hours ahead in July (AEST). Auckland is 5 hours ahead in January (NZDT) and 4 hours ahead in July (NZST).
In January: 09:00 HKT is 12:00 AEDT in Sydney and 14:00 NZDT in Auckland. 14:00 HKT is 17:00 AEDT in Sydney and 19:00 NZDT in Auckland. Sydney is fully covered; Auckland is covered until 17:00 NZDT.
In July: 09:00 HKT is 11:00 AEST in Sydney and 13:00 NZST in Auckland. 14:00 HKT is 16:00 AEST in Sydney and 18:00 NZST in Auckland.
The hard stop at 14:00 HKT
Booking a 16:00 HKT call puts Sydney at 19:00 AEST and Auckland at 21:00 NZST. After hours for both. The safe window closes at 14:00 HKT.
Best time to book
Aim for 10:00 HKT. Sydney is at 13:00 AEDT or 12:00 AEST, Auckland at 15:00 NZDT or 14:00 NZST. Everyone is post-lunch and alert.
What changes in April and October
Sydney changes clocks on the first Sunday in April and the first Sunday in October. When Sydney falls back in April, the gap shrinks from 3 hours to 2 hours. Your 09:00 HKT call becomes 11:00 AEST in Sydney instead of 12:00 AEDT. Adjust the HKT time later if you need Sydney at a specific hour.
How to plan a Hong Kong conference call when DST changes
The Time Zone Converters let you pick any date and see the exact offset for every city. Use them when the month changes, because the difference shifts.
Hong Kong to New York is 13 hours in January and 12 hours in July. If you schedule a quarterly call in February using January’s offset, you will be 1 hour off.
Set the calendar event to Asia/Hong_Kong
For a recurring monthly meeting, do not rely on memory. Set the meeting time in HKT and let participants convert to their local time. Most calendar apps handle this automatically if you set the event time zone to Asia/Hong_Kong.
Check the overlap twice for quarterly calls
Once at booking time and once a week before the meeting. The guides for Hong Kong vs London and Hong Kong vs New York have exact windows for each month.
The next US clock change that affects you
The end of daylight saving time in the US falls on 3 November 2026 (first Sunday in November). On that date, New York moves from EDT (UTC-4) back to EST (UTC-5). The Hong Kong to New York difference goes from 12 hours to 13 hours. If your meeting was at 21:00 HKT (09:00 EDT), it will become 21:00 HKT (08:00 EST). Your New York participants will arrive an hour early. Adjust the HKT time by 1 hour later to keep the same EST slot.
Mistakes that break a Hong Kong conference call schedule
Assuming same offset means same business hours
Singapore and Hong Kong share UTC+8. The overlap is full. But Dubai, also fixed at UTC+4 year-round, starts at 09:00 GST, which is 13:00 HKT. The overlap is not full. Check the local start time, not just the offset.
Booking during Hong Kong lunch
Hong Kong lunch is 12:30-14:00. New York lunch is 12:00-13:00 EST. If you book a 22:00 HKT call (10:00 EST), New York is fine. If you book 12:30 HKT (23:30 EST the previous day), you are scheduling during Hong Kong lunch and New York’s middle of the night.
Ignoring DST changes in other cities
Hong Kong stays fixed. London changes clocks on the last Sunday in March and October. New York changes on the second Sunday in March and the first Sunday in November. Sydney changes on the first Sunday in April and the first Sunday in October. Each change shifts the overlap window by 1 hour.
Forgetting that New York is not the whole US
Los Angeles is 16 hours behind Hong Kong in January and 15 hours behind in July. Chicago is 14 hours behind in January and 13 hours behind in July. A call booked for New York at 21:00 HKT (08:00 EST) puts Los Angeles at 05:00 PST. If you need the West Coast, push the call later or accept that they dial in from home.