Time Zone Overlap Calculator
See at a glance when Sydney, London, and New York are all in working hours - then pick the time that works for everyone.
How to use the Time Zone Overlap Calculator
- 1 Check the preloaded cities. Sydney, London, and New York are added by default. The colour-coded timeline shows where their working hours overlap right now.
- 2 Add or swap cities. Click + Add timezone to add another city, or click the city name on any card to replace it.
- 3 Drag the slider to explore times. Move the time slider left or right to scan through the day. Watch the timeline bars update in real time.
- 4 Pick a time where everyone is green. Green means standard business hours (9 am–5 pm). Find a slot where all your cities are green - that's your overlap window.
- 5 Create a meeting or share the link. Hit Create Meeting to add the event directly to Google Calendar, Outlook, or Teams, or copy a shareable link to send to your team.
Understanding working-hours overlap
When teams are spread across more than two continents, finding a time that works for everyone can feel impossible. Sydney is typically 10–11 hours ahead of London and 15–16 hours ahead of New York, which means a comfortable morning call for Sydney is often the middle of the night for New York.
The overlap window between Sydney and London is usually around 7–9 am London time (5–7 pm Sydney time). Between London and New York there is typically a five-hour overlap through the standard workday. Combining all three leaves a very narrow window - usually just one to two hours - so picking the right time matters.
Frequently asked questions
Add both cities to the planner. The colour-coded timeline shows green for standard working hours (9–5), amber for early morning or evening, and red for late night. Drag the time slider to find a slot where both cities show green.
Green means the time falls within standard working hours (9 am–5 pm). Amber indicates early morning or evening hours. Red means it is late at night. This makes it easy to spot a time that is acceptable for everyone at a glance.
Yes. TimezoneHelp lets you add up to five cities at once, so you can see the overlap across a whole global team in a single view.
Yes. All calculations use the IANA timezone database, which automatically handles daylight saving transitions for each region. Simply pick the date you are planning for and the offsets update accordingly.
Yes. Click the Share link button in the header to generate a URL that encodes your selected cities and chosen time. Anyone who opens the link will see exactly the same view.