Your computer already knows your UTC offset. It is the fixed difference, in hours and minutes, between your local wall-clock time and Coordinated Universal Time. Open the developer console right now (F12), paste new Date().getTimezoneOffset(), and press Enter. The number returned is your offset in minutes, positive for west of UTC, negative for east. Divide by 60 to get the familiar +hh:mm or -hh:mm format.

Your IANA time zone name

An offset is a snapshot. A time zone is a history. America/New_York is not just -05:00; it knows the offset becomes -04:00 during daylight saving and it knows every rule change since 1918. Two places sharing the same offset today can diverge next month.

Get your IANA zone name from the console with one line:

Intl.DateTimeFormat().resolvedOptions().timeZone

This returns something like Europe/London or Asia/Tokyo. The value comes from your operating system’s region settings, passed to the runtime environment. No network request. No permission dialog.

Is daylight saving time active right now?

Offset alone cannot answer that. You need your zone’s standard offset and the current DST status.

As of October 2026, the picture splits by region. In the United States and Canada, DST ends on the first Sunday of November. That is November 1, 2026. Until then, America/Chicago sits at -05:00 (CDT). After clocks fall back at 2:00 AM local time, it reverts to -06:00 (CST). In Europe, DST ended on the last Sunday of October, October 25, 2026. Europe/Berlin is already on standard time, +01:00, and stays there until the last Sunday of March 2027.

How the offset reaches your screen

The runtime environment reads the system clock from your operating system. The OS syncs that clock with an NTP server, but the environment does not make its own network call. It takes the instant from the OS and the zone from the OS region settings, then applies IANA time zone rules bundled in the engine.

The whole chain is local and immediate. If the OS clock is wrong or the region is misconfigured, every value on the screen will be wrong, no matter what the engine does.

Why your offset can shift next month

Governments change offsets. Usually for DST, sometimes permanently. The next change for most of North America is November 1, 2026, when clocks fall back one hour. For the United Kingdom and Ireland, the next change is March 28, 2027, when clocks spring forward.

If your zone observes DST, your offset shifts twice a year. If it does not (most of Asia, most of Africa), the offset stays constant. Check your zone’s IANA entry to know which camp you are in.