Meeting planner: when is everyone at work?

A time zone converter answers “what time is it there”. A meeting needs a different answer: which hours of the day are inside everyone's working hours, on the date you actually meet — because daylight saving moves the gap twice a year, and not on the same weekend everywhere.

Time differences people look up most

• New York and LondonLondon ahead by 5 hours · 3 hours of shared office time
• New York and SydneySydney ahead by 14–16 hours · no shared office hours
• New York and ParisParis ahead by 6 hours · 2 hours of shared office time
• London and Los AngelesLos Angeles behind by 8 hours · no shared office hours
• London and SydneySydney ahead by 9–11 hours · no shared office hours
• London and DubaiDubai ahead by 3–4 hours · 5 hours of shared office time
• London and BrisbaneBrisbane ahead by 9–10 hours · no shared office hours
• Sydney and SingaporeSingapore behind by 2–3 hours · 6 hours of shared office time
• New York and Los AngelesLos Angeles behind by 3 hours · 5 hours of shared office time
• New York and ChicagoChicago behind by 1 hour · 7 hours of shared office time
• New York and TokyoTokyo ahead by 13–14 hours · no shared office hours
• London and SingaporeSingapore ahead by 7–8 hours · 1 hour of shared office time

All 66 city pairs

Picking a time in four steps

Start with the two cities that cannot move. Put the person with the least flexibility first, because the first bar sets the day that every other bar is drawn against. Then add the remaining cities one at a time and watch how the shaded “everyone at work” stretch narrows with each addition. Two cities usually leave a window of several hours; three cities spread across the Atlantic and the Pacific often leave one or two; four or five can leave none, and that result is information too — it tells you the meeting needs a rotating start time rather than a single perfect hour.

Next, set the date to the day of the meeting, not today. A call planned for the third week of March can sit in a stretch where New York has already moved its clocks and London has not, so the same hour pair that works in February is an hour off. Finally, drag across the bars and read the time in every city before you commit. Copy time gives you a line you can paste into an invite, and Copy link reopens the same cities and date for a colleague.

How daylight saving is handled

The planner does not apply a rule such as “London is five hours ahead of New York”. For each quarter-hour of the chosen day it asks your browser what the offset from UTC is in each city on that exact date, using the IANA time zone database. That database stores every zone as a history of offsets and transition moments, so a zone that changed its rules, moved its change date, or dropped daylight saving altogether is handled by the same lookup as an ordinary one.

The practical result is that the gap between two cities is shown for the day you pick, and the odd weeks appear without any special case. In March and again around the end of October the United States, Canada and Europe are on different clocks for a short stretch, and the pair pages for cities such as Chicago and Paris show exactly which weekends those are. Cities near the equator, such as Singapore, never change, which is why the gap to Singapore moves by an hour whenever the other city changes.

Tips for recurring meetings

A weekly call is the case where daylight saving does the most damage. Most calendar tools store a recurring event in one time zone, which means everyone else sees it jump by an hour when either side changes its clocks. Decide up front whose local time is the anchor — usually the organiser’s or the largest group’s — and say so in the invite, so that nobody is surprised when the same invitation lands an hour earlier on their own clock for a few weeks.

Check the two or three weeks around each clock change by setting the date in the planner and looking at the bars. If the shared window is only an hour wide, a one-hour shift can remove it entirely, and it is better to find that out before the first awkward call than after. When the overlap is thin, alternate the inconvenient slot between regions instead of always asking the same team to join early or late.

Remember that “working hours” differ by country. Start at 9:00 and end at 17:00 as a default, then edit the hours of any city whose team starts later or runs shifts; the shaded bars follow your edits. Lunch breaks are not modelled, so leave a margin of half an hour on each side of a window you intend to use.

What the planner deliberately leaves out

Public holidays are not marked, and neither are local customs such as a shortened Friday or a mid-week rest day. Weekends are Saturday and Sunday everywhere; a few countries use Friday and Saturday or Friday alone, and for those cities you will need to judge the weekday yourself. The city list holds a few hundred larger places, not every town, so a small town should be mapped to the nearest listed city that shares its time zone.

Nothing here books a room, sends an invitation or reads your calendar. The tool only answers one question — when are these people awake and at work at the same moment — and leaves the rest to the calendar you already use.

Questions

Why does the bar for a city start at a different time than my own? Because every bar is drawn against the same real moments. A city that is ahead of the first one reaches its midnight earlier, so its day appears shifted to the left, and a bold weekday label marks the point where its date changes.

Can I plan for a date months away? Yes, with one caveat: the browser’s database knows the rules currently in force. If a country announces a change, a browser that has not updated may not yet know it.

Do my saved lists leave my device? No. Saved lists are kept in your browser’s own storage on this device, and nothing about the cities you choose is sent to a server.

City names, coordinates and time zone assignments: GeoNames, licensed under CC BY 4.0 (selection and renaming of some cities by this site). Clock times are computed in your browser from the IANA time zone database. Sources and limits.