OnSumo Tools

Time Zone Meeting Planner

Map working hours across locations on one UTC grid and spot when everyone is free at once.

Meeting settings

Locations

Overlap grid (UTC hours)

Green = all locations in working hours. Amber = some overlap. Gray = off hours.

Location01234567891011121314151617181920212223
New York
20
21
22
23
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
London
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
0
Overlap

Best meeting slots

  • UTC 13:00–17:00 (240 min)

    • New York: 9 AM – 1 PM
    • London: 2 PM – 6 PM

Offsets follow the IANA time zone database for your chosen date. Confirm the final time with attendees before you send invites.

How this tool works

The tool maps each location's working hours to UTC for the reference date, then identifies UTC hours where all locations are simultaneously within their working windows.

Worked example

Reference date: June 4, 2026 (both cities observing summer time)

Related tools

Frequently asked questions

  • How does the overlap grid work?

    Each row in the grid represents one location. Each column represents one UTC hour of the day (0-23). The cell color shows whether that location is within its configured working hours at that UTC time. Green columns are the hours where every location in your list is simultaneously in their working window. Those are your best meeting slots.

  • What about daylight saving time?

    The planner uses the IANA timezone database with your selected reference date to calculate exact offsets for every location on that specific day, including DST. A location's offset may shift by one hour between a winter and summer date. Always select the actual planned meeting date, not today's date, when the meeting is scheduled in advance.

  • What if there is no overlap?

    The tool shows \"No mutual business hours\" and displays which partial-overlap bands come closest. It identifies the earliest morning slot for one group and the latest evening slot for the other to help negotiate a mutually acceptable outside-hours time. No overlap is common between East Asian and North American teams regardless of business hours.

  • What should I do when the meeting must happen at a specific UTC time regardless of local hours?

    Enter the required UTC time and look at the grid to see what local time that corresponds to for each participant. The grid displays all 24 UTC hours and their local equivalents for each location, so you can read off exactly what time a given UTC hour lands in each participant's city. This is useful for scheduled maintenance windows, coordinated deployments, or any event driven by a fixed UTC timestamp rather than local business hours.

  • How do I account for a participant who is traveling and temporarily in a different time zone?

    Add a separate entry for that participant using their travel destination's timezone rather than their home location. You can label the row with their name and a note like \"(in Singapore this week)\" to avoid confusion. The tool treats each row as an independent location; it does not need to be a permanent address. Change the entry back to their home timezone after they return.

  • Why does the tool use IANA timezone names instead of UTC offsets?

    UTC offsets are ambiguous across the year because of daylight saving time. America/New_York is UTC-5 in winter and UTC-4 in summer; entering UTC-5 for a summer meeting would produce the wrong result. IANA timezone names encode the full historical and future DST transition rules for each location. Using the IANA name guarantees the correct offset for the specific reference date you enter, even for dates months in the future when DST transitions may have already occurred.