Meeting Time Zone Planner

How the planner scores each hour

Add the cities where your participants are based and pick a day. The tool looks at each of the 24 hours of that day and works out what the local time is for everyone, using your browser's built-in time zone data, so daylight saving rules are applied correctly for the date you chose. Each local hour then gets a burden score: 0 for core working hours (09:00 to 18:00), 1 for shoulder hours (08:00 to 09:00 and 18:00 to 20:00), 2 for early or late hours (06:00 to 08:00 and 20:00 to 22:00), and 3 for night (22:00 to 06:00).

The scores for all participants are added up to give the slot's total burden, out of a maximum of 3 for each person. The best slots are the ones with the lowest total, and slots where anyone would be in the middle of the night are left out unless there is no alternative. The heatmap colours each hour as great, okay, poor or bad so you can see the whole day at a glance, and a fairness bar shows who is carrying the inconvenience.

A worked example

London and New York, when both are on standard time, are five hours apart. The only start times where both people are in core working hours are 14:00 to 17:00 London time, which is 09:00 to 12:00 in New York, so those four slots score 0.

Now take New York and Singapore, which are 13 hours apart in winter. There is no hour when both are at work. The lowest total burden is 2 out of a possible 6, at 19:00, 20:00 and 21:00 New York time, which is 08:00, 09:00 and 10:00 the next morning in Singapore. The tool shows these as shoulder-hour options, and the fairness bar makes it clear that New York is giving up the evening.

Daylight saving warnings

Recurring meetings often go wrong in the weeks when countries change their clocks on different dates. The US and the UK, for example, switch several weeks apart in spring and autumn, so the gap between London and New York is briefly four hours instead of five. The planner looks 30 days ahead for each time zone and shows a warning if any participant's clock is about to shift. The check samples one day at a time, so the transition date it shows is accurate to within about a day.

Limits

The burden scale is a rule of thumb. It assumes a nine-to-five day and ignores things like lunch breaks, school runs, public holidays, weekends in countries with a different working week, and personal preferences, so treat the result as a shortlist and not a verdict. The list covers around 80 major cities, with several sharing a time zone, and times are calculated on your device, so nothing about your meeting is sent anywhere. Slots start on the hour, so half-hour time zones such as India are shown correctly but meeting times at :30 are not offered.