Asia/Tehran

TZ identifier and aliases

Asia/Tehran is the canonical identifier for Iran Standard Time, covering the entire country. The bare country name Iran is an older name still pointing at the same rules but is a deprecated alias — use Asia/Tehran in new code.

UTC offset and DST rule

Asia/Tehran is +03:30 year-round with no daylight saving time — one of only a small number of half-hour UTC offsets used anywhere in the world, alongside India's +05:30. Iran abolished daylight saving for the second time on September 21, 2022, and has kept this single fixed offset since — there's no seasonal clock change to account for in any system built against this zone today.

Using it in cron, CI and Postgres

Set TZ=Asia/Tehran for a process that should schedule by Iranian local time — the half-hour offset is the main thing to watch for in code that assumes all time zone offsets fall on whole hours, an assumption that breaks here just as it does for India. Postgres accepts it via SET TIME ZONE 'Asia/Tehran'; or the timezone setting and handles the half-hour offset correctly by default. Because the offset is currently fixed, a cron job's local-time schedule behaves identically every day of the year — worth double-checking any system with DST-adjustment logic left over from before 2022, since that code is now dead weight or, if still active by mistake, silently wrong.

History and quirks

Iran's +03:30 offset is deliberately defined by the 52.5°E meridian, which not coincidentally also anchors the Iranian solar calendar — a rare case of a country's time zone and its entire calendar system sharing the same geographic reference point. Iran abolished DST once before, in the 2000s, then reintroduced it, before abolishing it for a second and — so far — final time on September 21, 2022. Officials cited public confusion and limited energy savings as the reasoning, a rationale echoed almost word-for-word by Turkey, Russia and Egypt at various points in their own recent DST reversals, suggesting a broader regional pattern away from seasonal clock changes across the Middle East and parts of Eastern Europe over the past decade. Because the change is so recent, older software and scheduling systems built against Iran before 2022 may still carry now-incorrect seasonal offset logic that's worth auditing specifically.

Offsets and DST transitions on this page are computed from the IANA time zone database bundled with your browser; the rules described above were verified against tzdata 2026b when this page was published.