GMT vs UTC
Astronomy versus atomic clocks, leap seconds and their planned end, and which to write.
BST vs GMT
UK clock changes for 2026–2028, what happens on the change nights, and how to write UK times.
BST vs EST
Why London and New York are usually 5 hours apart but sometimes 4, with exact dates.
EST vs PST
The US time zones, Arizona and Hawaii, and the 2026 changes in Canada.
Daylight saving time explained
History, dates around the world, and the countries that have recently stopped.
Planning meetings across time zones
Overlap windows, clock-change traps, fair rotation and asynchronous work.
Time zone FAQ
Short answers about offsets, abbreviations, the date line and recent rule changes.
Where to start
- Working with the US from the UK? Read BST vs EST, then use the meeting planner.
- Confused by "GMT" in a summer invitation? BST vs GMT explains it.
- Writing software or logs? GMT vs UTC covers UTC, offsets and leap seconds.
For abbreviations such as CET, IST or AEST, see time zone abbreviations.