ShipZume
Reference library

Time zone guides

Ten reference guides covering the parts that actually cause trouble: seasonal clock changes, ambiguous abbreviations, the date line and the software bugs that follow from all three.

Daylight saving explained

Which countries change their clocks, when they do it, and why the same two cities can be five hours apart one week and six the next.

UTC, GMT and Zulu time

What UTC actually is, how it differs from GMT, why aviation says Zulu, and when the distinction matters.

Scheduling across time zones

A practical method for booking meetings across zones: finding the overlap, rotating the pain, and stopping recurring calls from drifting.

Why abbreviations are ambiguous

IST means three different things, CST means three more. Which abbreviations are ambiguous and what to use instead.

The International Date Line

Why crossing one line changes the date, how a flight can arrive before it left, and which places are furthest apart in time.

Remote work across zones

How distributed teams actually handle time differences: core hours, async defaults, handovers and the failure modes to avoid.

Jet lag and travel planning

Why eastward flights hurt more, how long adjustment actually takes, and how to plan arrivals around the time difference.

Market trading hours

When the major exchanges open in your local time, where the sessions overlap, and why daylight saving moves the open twice a year.

Timestamps for developers

How to store, transmit and display time in software without creating bugs: UTC storage, IANA zones and ISO 8601.

Half-hour time zones

India at UTC+5:30, Nepal at UTC+5:45, Chatham at UTC+12:45 — which places use fractional offsets and why.

US time zones explained

The six US time zones, which states split between two, where daylight saving does not apply, and how the gaps shift twice a year.

European time zones

WET, CET and EET, why Spain is an hour off the sun, and how EU clock changes differ from the American dates.

How these guides are written

Each one starts from a real scheduling failure, uses the IANA database and primary legislation for its figures, and is reviewed before publication.

1

Question first

Each guide starts from a real search — the thing people actually need to settle.

2

Official figures

Definitions come from standards bodies, not from other websites.

3

Worked examples

Numbers are shown in context so you can check the maths yourself.

4

Reviewed twice

Every figure is verified by a second person before publication.

Prefer a straight answer?

Go to the directory and pick the exact zone pair you need.

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