How to Schedule Meetings Across Time Zones (Without the Headache)
"Let's sync up" means very different things to someone in New York, London, and Tokyo. The math of time zones isn't hard — it's the details (DST, half-hour offsets, overnight shifts) that trip people up. Here's a practical system for finding the time that works for everyone, and why doing it in your browser beats handing your calendar to another app.
Start with UTC, Not With Any City
Every time zone on Earth is described by its offset from UTC. UTC is the reference clock that doesn't observe daylight saving. Once you think of each city as "UTC plus some number", comparing them becomes simple subtraction.
| City | Summer offset | Winter offset |
|---|---|---|
| New York | UTC−4 (EDT) | UTC−5 (EST) |
| London | UTC+1 (BST) | UTC+0 (GMT) |
| Paris | UTC+2 (CEST) | UTC+1 (CET) |
| Tokyo | UTC+9 (JST) | UTC+9 (JST, no DST) |
| Mumbai | UTC+5:30 | UTC+5:30 (no DST) |
| Sydney | UTC+10 (AEST) | UTC+11 (AEDT, southern summer) |
Note the trap in that table: the offsets are swapped for the southern hemisphere. Sydney is UTC+10 in their winter and UTC+11 in their summer — which coincides with the northern winter. DST is a local decision, not a global one.
The Overlap Method: Convert, Then Intersect
- 1 Pick everyone's working window. Usually 9 AM – 5 PM local, but shift it to match reality — a customer-facing team might be 8–4, an ops team might be 10–6.
- 2 Convert every window into UTC. New York 9–5 in summer becomes 13:00–21:00 UTC. London 9–5 becomes 08:00–16:00 UTC. Tokyo 9–5 becomes 00:00–08:00 UTC.
- 3 Find the intersection. NYC ∩ London = 13:00–16:00 UTC. Tokyo doesn't intersect either in summer — which is exactly the reality every remote team eventually discovers.
That last point matters: sometimes there is no good overlap, and knowing that early saves everyone an awkward calendar invite. A tool that shows you the truth in two seconds is worth more than one that politely pretends 3 AM works for someone.
Daylight Saving: The Reason Fixed Offsets Lie
A static table of "New York = UTC−5" is wrong for half the year. Real scheduling needs the IANA time zone database — the same rules your operating system uses — which encodes exactly when each region springs forward and falls back. Europe shifts on the last Sunday of March and October; North America on the second Sunday of March and the first Sunday of November; and the two never align, so the New York–London gap is 5 hours in summer and 5 hours in winter, but 4 hours for the two weeks between the transitions.
The Prescosoft Time Zone Planner uses the IANA database through your browser's native Intl API, so every conversion — including those weird two-week gaps — is correct by construction.
A Two-Minute Scheduling Workflow
Add the zones
Search by city — New York, London, Tokyo. Each shows a live clock and its current UTC offset, so nothing is guesswork.
Read the overlap grid
The 24-hour grid marks each zone's working hours. The solid columns are when everyone is available. Click one to set the meeting.
Confirm conversions
The converter shows the exact local time in every zone, including day shifts — "3 PM London = 10 AM New York."
Copy and invite
Copy the full summary with every zone's time and offset, and paste it straight into the invite.
Why Schedule in Your Browser?
- Calendar-integrated schedulers ask for an account and often full calendar, contacts, and email access to do one simple conversion.
- That access means your schedule and meeting data live on someone's servers.
- A local planner needs none of it — the math runs in your browser via the Intl API, and nothing is uploaded.
- Works offline, no account, and your selections vanish when you close the tab.
Frequently Asked Questions
What is the best way to schedule a meeting across time zones?
Pick a reference zone, choose a candidate time, then check what that instant looks like in every other zone. The most reliable approach is to find the overlap of everyone's working hours — a 24-hour grid that marks each zone's 9-to-5 makes the shared window visible at a glance, and tools like the Prescosoft Time Zone Planner highlight it automatically.
How do UTC offsets work?
UTC is the global reference clock. Every time zone is described by its offset from UTC — New York is UTC-4 in summer and UTC-5 in winter, London is UTC+1 in summer and UTC+0 in winter, Tokyo is UTC+9 year-round. Two places differ by the difference between their offsets at the moment you're comparing.
Why do time zone conversions change through the year?
Daylight saving time. Zones that observe DST shift their offset twice a year, and not all countries shift on the same dates. Europe and North America change on different weekends, and some regions don't observe DST at all. That's why scheduling tools use the IANA time zone database rather than a fixed offset table.
How do I find working hours that overlap across several zones?
Convert everyone's 9-to-5 window into a common reference (UTC) and look for the intersection. For example, New York (13:00–21:00 UTC in summer) and London (08:00–16:00 UTC) overlap from 13:00 to 16:00 UTC — three solid hours. The Time Zone Planner's overlap grid does this comparison for every hour of the day across all added zones.
What's the difference between a time zone and a UTC offset?
A UTC offset is just a number describing the difference from UTC at one moment. A time zone is the full set of rules for a region — including when DST starts and ends, and what the offset is during each period. Europe/London and Europe/Paris both follow EU DST rules but have different base offsets, so they can never be reduced to a single fixed number.
Is it safe to use a website to plan meetings across time zones?
Yes, if the site does the math locally. The Prescosoft Time Zone Planner runs entirely in your browser using the built-in Intl API — your zone selections and meeting times are never uploaded. Calendar-integrated schedulers, by contrast, ask for account access to your calendar and contacts.
Find the time that works for everyone — privately
400+ time zones, live clocks, and an overlap grid that shows the truth in seconds. Nothing is uploaded.