What is the difference between a Unix timestamp and a local time?

A Unix timestamp is a count of seconds since 1 January 1970 00:00:00 UTC. It carries no timezone. Local time is the wall clock reading in a specific zone. Converting one to the other demands the zone's offset and DST rules at that exact moment.

How do I convert a timestamp to Mountain Time in code?

Use the IANA zone `America/Denver`. In Python: `from datetime import datetime; from zoneinfo import ZoneInfo; dt = datetime.fromtimestamp(ts, ZoneInfo("America/Denver"))`. In JavaScript: `new Date(ts * 1000).toLocaleString("en-US", { timeZone: "America/Denver" })`.

Is Phoenix on Mountain Time?

Yes. Phoenix uses `America/Phoenix`, which stays on MST (UTC-7) year-round. Phoenix does not observe DST. In July, Phoenix is one hour behind Denver.

What should I do if my timestamp falls in the DST gap?

During the spring-forward transition, the hour from 02:00 to 03:00 does not exist. A timestamp mapping to that hour produces an invalid local time. Most libraries throw an error or return the next valid time. Use a timestamp outside the gap.

Where can I see the current Mountain Time offset?

The live clocks show the current offset (MST or MDT) and the exact local time in Denver. The MST Offsets page lists the UTC offset for every IANA zone in the Mountain Time metazone.

MST Timestamp Converter

Denver and Phoenix are not the same hour in July. A timestamp that reads 12:00 in Denver reads 11:00 in Phoenix. The number itself does not change. The offset you apply does. Hold onto that single fact when converting a Unix timestamp to Mountain Time.

What is a Unix timestamp?

A single integer. The count of seconds elapsed since 1 January 1970 00:00:00 UTC. No timezone, no DST flag, no country code. Databases, APIs, and server logs store timestamps this way precisely because the number is unambiguous. A given timestamp names the same instant in Tokyo, London, and Calgary. The wall clock reading differs. The moment does not.

How to convert a timestamp to Mountain Time

Use the IANA zone identifier America/Denver for most of the Mountain time zone. That one string encodes the full DST history: when clocks spring forward, when they fall back, and the correct UTC offset for any instant.

The conversion runs in three steps:

Take your Unix timestamp. Interpret it as UTC.
Determine the active offset for that date. On 1 January 2026, America/Denver is on Mountain Standard Time, offset UTC-7. On 1 April 2026, it is on Mountain Daylight Time, offset UTC-6.
Apply the offset to get local wall clock time.

The same timestamp converted for a date in January yields MST. Convert it for a date in July and you get MDT. Hardcoding a single offset gives you the wrong answer for half the year.

Why your timestamp is always UTC

Storing a moment as a bare wall clock string ("2026-04-01 06:00:00") without an offset is ambiguous. Is that 06:00 in Denver, New York, or London? Nobody can tell. Storing the UTC epoch removes the guess. Any system, anywhere, can convert that integer to its own local time.

One mistake to avoid: appending an abbreviation like "MST" to a stored timestamp. The string "MST" can mean Mountain Standard Time (UTC-7) or Malaysian Standard Time (UTC+8). Store the numeric epoch, or store ISO 8601 with an explicit offset like -07:00. Skip the abbreviation.

How to use the converter

Paste a Unix timestamp. Get back the human-readable time for America/Denver. The converter handles DST transitions automatically and shows whether the current offset is MST or MDT.

Two edge cases to watch for. During the spring-forward gap (the hour from 02:00 to 03:00 on Sunday 8 March 2026), the local time does not exist. The converter flags that. During the fall-back overlap (01:00 to 02:00 on Sunday 1 November 2026), the local time happens twice. The converter shows the first occurrence in MDT and the second in MST. Pick the one you need.

When a fixed offset breaks your MST timestamp conversion

The most common error in timestamp conversion is subtracting a constant number of hours. Mountain Time is not always UTC-7. From Sunday 8 March 2026 to Sunday 1 November 2026, it is UTC-6. Hardcode -7 and your conversions are wrong all summer. Pass America/Denver to your datetime library and let the IANA database do the work.

Phoenix or Ciudad Juárez: why the same timestamp shows a different hour

Arizona, represented by America/Phoenix, stays on MST (UTC-7) year-round. No DST. In July, when Denver runs on MDT (UTC-6), Phoenix is one hour behind Denver. The same timestamp yields a different wall clock in each city.

Ciudad Juárez (America/Ciudad_Juarez) follows US DST rules to stay aligned with El Paso. The rest of Mexico abolished DST in October 2022, but the northern border kept it.

For Calgary or Edmonton, use America/Edmonton. The converter defaults to America/Denver. Swap the zone if your location differs.

Does "MST" in a log file mean Mountain Time?

Not reliably. "MST" is the abbreviation for Mountain Standard Time (UTC-7). During summer the correct abbreviation is MDT (Mountain Daylight Time, UTC-6). If a log file prints "MST" in July, treat it as a bug. The abbreviation is ambiguous. The IANA zone name is not. When you need certainty, use the offset (-07:00 or -06:00) or the full IANA identifier.

Converting pre-1970 timestamps with the MST converter

DST rules change. The IANA database tracks every historical transition. The converter uses IANA data current as of September 2026. Feed it a timestamp from 1970 and it applies the rules that were in effect on that date. That is the correct behaviour. No special handling required.