A Practical Guide to Working Across Time Zones

Distributed teams lose more time to scheduling mistakes than to any other logistical problem. Almost all of them come from four causes: ambiguous abbreviations, forgotten daylight saving shifts, guessing at the offset, and picking a time that’s technically possible but genuinely unpleasant for one side. Each is avoidable.

Never write only an abbreviation

Time zone abbreviations are not unique, and several of the common ones collide:

Abbreviation	Could mean	Or
CST	Central Standard Time (US, UTC−6)	China Standard Time (UTC+8)
IST	India Standard Time (UTC+5:30)	Israel or Irish Standard Time
AST	Atlantic Standard Time (Canada)	Arabia Standard Time
BST	British Summer Time (UTC+1)	Bangladesh Standard Time (UTC+6)
EST	Eastern Standard Time (US)	Eastern Standard Time (Australia)

A meeting invitation reading “10 AM CST” sent between a US and a Chinese office is genuinely ambiguous by 14 hours. Always name a city: “10 AM Chicago time” or “10 AM Central (US)” cannot be misread. Better still, send a calendar invite — every calendar application converts to each attendee’s local time automatically, which removes the arithmetic completely.

The other half of the confusion: standard vs daylight

“EST” strictly means Eastern Standard Time, which New York only observes from November to March. From March to November it’s EDT, one hour ahead. Most people write EST year-round without thinking about it, which is fine in casual use and dangerous in a contract.

If precision matters, write the offset: “14:00 UTC” is unambiguous everywhere and never shifts. UTC is why aviation, shipping and most server logs use it exclusively.

Daylight saving breaks recurring meetings

This is the subtlest trap. Regions change their clocks on different dates:

• US and Canada: second Sunday in March → first Sunday in November.
• UK and EU: last Sunday in March → last Sunday in October.
• Australia (southern states): the opposite hemisphere, so first Sunday in October → first Sunday in April.
• India, China, Japan, most of Africa and South America, Arizona and Hawaii: no daylight saving at all.

The consequence: New York and London are usually 5 hours apart, but for about two weeks in March and one week in late October they’re 4 hours apart. A weekly call that’s always been “2 PM London, 9 AM New York” silently becomes 8 AM New York for those weeks unless the calendar entry was created with proper time zones.

The fix is to set recurring meetings in a calendar that stores the organiser’s zone — never as a fixed UTC offset, and never by writing the time in a document. And when the shift weeks come round, verify with the time zone converter, which applies the exact rules for the date you enter.

Where the overlap actually is

For a normal 9–5 working day, these are the practical windows:

Pair	Overlap	Best meeting time
US East ↔ US West	5 hours	12–4 PM Eastern (9 AM–1 PM Pacific)
US East ↔ UK	3–4 hours	8–11 AM Eastern (1–4 PM London)
US East ↔ Central Europe	2–3 hours	8–10 AM Eastern (2–4 PM Berlin)
US East ↔ India	~1 hour, strained	8–9:30 AM Eastern (5:30–7 PM India)
US West ↔ India	Almost none	8:30–9:30 PM Pacific (9–10 AM India)
UK ↔ India	4 hours	10 AM–2 PM London (3:30–7:30 PM India)
UK ↔ Australia East	~1 hour	8–9 AM London (6–7 PM Sydney)
US East ↔ Australia East	None in working hours	5–7 PM Eastern (7–9 AM Sydney, next day)

Anything spanning more than about eight hours means someone takes the call outside normal hours. When that’s unavoidable, rotate who suffers rather than always imposing on the same side — the team furthest from headquarters usually absorbs it by default, and it wears people down.

Practical habits that prevent mistakes

• Send calendar invites, not times in messages. The invite carries the zone; a Slack message doesn’t.
• State both zones when you must write a time: “Thursday 3 PM London / 10 AM New York.”
• Watch the date line. 9 AM Monday in Los Angeles is 2 AM Tuesday in Sydney. Confirm the day, not just the hour.
• Add a second clock to your phone or laptop for the zone you work with most. Ten seconds to set up, and it removes the mental arithmetic entirely.
• Default to asynchronous. A written update that anyone can read at their own morning is better than a meeting that’s the wrong hour for half the participants.
• Record what can’t be attended live and share notes, so people outside the window aren’t permanently disadvantaged.
• For deadlines, give a zone and a date: “by 17:00 UTC on 12 March”, not “end of day Thursday” — end of day where?

Quick reference

UTC is the anchor everything else is defined against. To go from UTC to local, add the offset: New York is UTC−5 (−4 in summer), London UTC+0 (+1 in summer), Berlin UTC+1 (+2), India UTC+5:30 all year, China and Singapore UTC+8, Japan UTC+9, Sydney UTC+10 (+11 in their summer).

For anything else, the time zone converter handles the date, the daylight-saving rules and the day shift for you, and there are dedicated pages for the most common pairs such as PST to EST, EST to IST and GMT to AEST.