Guides
How time zones actually behave, and how to work across them. Written by the person who builds the tools on this site, mostly in response to getting it wrong first.
How Time Zones Actually Work (And Why 9am Is Never Just 9am)
Offsets, UTC, daylight saving and the political side of time zones, explained without the jargon, so cross-border scheduling stops surprising you.
Fundamentals · 8 min read
The Best Meeting Times for India and US Teams
The real overlap between Indian and American working hours, hour by hour, and which slots cost somebody their evening. Written for teams that meet weekly, not once.
Remote work · 9 min read
UTC, GMT and Zulu Time: What the Difference Actually Is
Three names that look interchangeable, one real technical distinction, and the one situation where using the wrong one matters.
Fundamentals · 6 min read
The Time Zones That Are Not Whole Hours
India, Nepal, Newfoundland, the Chatham Islands and the rest of the thirty and forty five minute offsets, why they exist and what they break in software.
Fundamentals · 7 min read
Daylight Saving Time: Who Changes, When, and Why It Keeps Catching You Out
Which countries still move their clocks, the dates they do it, why the changeovers do not line up, and how to stop recurring meetings drifting.
Fundamentals · 8 min read
Scheduling Across Three or More Time Zones Without Anyone Taking a 3am Call
A practical method for finding the least bad meeting slot when two zones already have no overlap, plus when to stop meeting and start writing.
Remote work · 7 min read
Why Time Zone Abbreviations Like CST and IST Are Genuinely Dangerous
The same three letters can mean zones hours apart, and often encode the season too. A short guide to the worst offenders and what to write instead.
Fundamentals · 6 min read
How to Store a Timestamp So It Still Makes Sense Next Year
Why local time in a database is a bug, what to do about recurring events, and the two hours a year that break naive datetime handling.
For developers · 7 min read
Why these guides exist
Every tool on this site started as a question somebody actually had: what time is the call, why did it move, why does my code get India wrong. The calculators answer the question. These pages explain the thing underneath it, so the answer makes sense rather than just appearing.
They are written by hand, one at a time, by Nishanth Narayanan. Nishanth Narayanan builds and maintains GlobalTimeTools from Coimbatore, India. He works with distributed teams across Indian, European and US time zones, which is where most of these questions came from.