PST vs PDT

What PST stands for

PST is the abbreviation for Pacific Standard Time, eight hours behind Coordinated Universal Time (UTC-8). It applies from the first Sunday of November to the second Sunday of March. That is a little over four months — which is why "PST" written on a June invitation is, strictly speaking, wrong.

What PDT stands for

PDT is the abbreviation for Pacific Daylight Time, seven hours behind UTC (UTC-7). It applies from the second Sunday of March to the first Sunday of November — nearly eight months of the year, and the form most people should be writing most of the time.

Which one applies today?

• Second Sunday of March to first Sunday of November → PDT. In 2026, March 8 to November 1.
• First Sunday of November to second Sunday of March → PST. In 2026–27, November 1 to March 14.

The clocks move at 2:00 a.m. local time on those Sundays. Dates for the coming years are on the daylight saving time page, and the live Pacific clock on the homepage already reflects whichever form is currently in force.

PST vs PDT at a glance

Is "West Coast time" the same as Pacific Time?

In everyday use, yes. "West Coast time" is an informal name for the Pacific zone, and the abbreviation people mean by it is PST or PDT — or, better, the neutral PT. It is not an official designation, so it never appears in a legal or technical context; when precision matters, write PT, PST, PDT, or the identifier America/Los_Angeles.

One thing "West Coast" does not cover cleanly: not every state with a Pacific coastline is entirely in the Pacific zone, and Alaska — very much a west-coast state — is on Alaska Time, an hour further behind.

Where the Pacific zone applies

California, Nevada and Washington are entirely on Pacific Time. Oregon is almost entirely Pacific, with most of Malheur County in the far east on Mountain Time. Idaho's northern Panhandle is on Pacific while the rest of the state is on Mountain. So the answer to "what is the California time zone abbreviation" is PST in winter and PDT in summer — and PT if you would rather not have to check. The US states time zones list covers every state and the split-state boundaries.

When to write PT instead

PT — Pacific Time — drops the standard/daylight distinction and stays correct all year. It is the right choice for business hours, recurring meetings, product launch windows, and anything else without one fixed date. "Doors open 9 a.m. PT" needs no seasonal maintenance; "9 a.m. PST" quietly goes wrong every March.

Reserve PST and PDT for statements anchored to a specific date, where being an hour out has a real cost.

Common Pacific time mistakes

• Using PST year-round. The most frequent error in US time-zone writing. For most of the calendar, PDT is the accurate form.
• Pairing PST with EDT. "1 p.m. EDT / 10 a.m. PST" mixes a daylight form with a standard form and describes no real moment. Pick one frame, or use ET and PT.
• Assuming the three-hour gap changes. It does not. Pacific is three hours behind Eastern all year, because both zones shift on the same dates.
• Treating Arizona as Pacific in summer. Phoenix reads the same clock time as Los Angeles from March to November, but it is MST, not PDT. The Arizona case is covered on the abbreviations reference.
• Storing UTC-8 for a future appointment. Store America/Los_Angeles instead, and let the library resolve the offset. See UTC and U.S. time.

The same pattern in every other zone

Pacific is one of four continental zones, and all four work the same way: EST and EDT for Eastern, CST and CDT for Central, MST and MDT for Mountain. The full list — including Alaska, Hawaii and the territories — is on the US time zone abbreviations page.

The one-line rule

If the date falls between the second Sunday of March and the first Sunday of November, write PDT. Otherwise write PST. If there is no fixed date, write PT.

To convert a specific time between Pacific and any other US zone, use the time zone converter. For coast-to-coast meeting planning, see scheduling across U.S. time zones.