CET to IRST Time Converter
IRST is 1 hour and 30 minutes ahead of CET. Continental western Europe is currently on CEST (UTC+2:00), and IRST is UTC+3:30.
Best Time to Call Between CET and IRST
Both zones are inside normal business hours between 9:00 AM and 4:00 PM CET — that's 10:30 AM to 5:30 PM IRST. That's a 7-hour window.
both at work CET only IRST only neither — hours along the strip are CET.
Common Times Converted
CET on the left, IRST on the right.
CET to IRST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| CET | IRST | Working hours |
|---|---|---|
| 12:00 AM | 1:30 AM | — |
| 1:00 AM | 2:30 AM | — |
| 2:00 AM | 3:30 AM | — |
| 3:00 AM | 4:30 AM | — |
| 4:00 AM | 5:30 AM | — |
| 5:00 AM | 6:30 AM | — |
| 6:00 AM | 7:30 AM | — |
| 7:00 AM | 8:30 AM | — |
| 8:00 AM | 9:30 AM | IRST only |
| 9:00 AM | 10:30 AM | Both zones |
| 10:00 AM | 11:30 AM | Both zones |
| 11:00 AM | 12:30 PM | Both zones |
| 12:00 PM | 1:30 PM | Both zones |
| 1:00 PM | 2:30 PM | Both zones |
| 2:00 PM | 3:30 PM | Both zones |
| 3:00 PM | 4:30 PM | Both zones |
| 4:00 PM | 5:30 PM | CET only |
| 5:00 PM | 6:30 PM | — |
| 6:00 PM | 7:30 PM | — |
| 7:00 PM | 8:30 PM | — |
| 8:00 PM | 9:30 PM | — |
| 9:00 PM | 10:30 PM | — |
| 10:00 PM | 11:30 PM | — |
| 11:00 PM | 12:30 AM next day | — |
What CET and IRST Actually Are
CET — Central European Time
Paris, Berlin, Madrid, Rome, Amsterdam, Vienna, Warsaw, Stockholm. Standing at UTC+1:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, October 25, 2026, to CET. Most of continental Europe moves to CEST (UTC+2) for the summer.
Central European Time spans a remarkable stretch of longitude — from Spain's Atlantic coast to Poland's eastern border — so solar noon in Madrid arrives nearly two hours later than in Warsaw.
IRST — Iran Standard Time
Tehran, Mashhad, Isfahan. Standing at UTC+3:30 as written, and the region does not change its clocks, so that offset holds all year. Iran abolished daylight saving in 2022, so the half-hour offset now holds all year.
Iran abolished daylight saving in 2022. Its half-hour offset is a deliberate compromise between the solar times of its western and eastern borders.
What This Means in Practice
Expect times on the half hour
IRST sits on a 30-minute offset rather than a whole hour, so a round number on one side is never a round number on the other. A 9:00 meeting becomes 30 minutes past the hour, which is exactly the detail calendar invitations get wrong when someone converts in their head.
This gap is not fixed
CET changes its clocks and IRST does not, so the difference between them moves by an hour twice a year. A recurring meeting set now will drift for one side from Sunday, October 25, 2026 unless someone resets it.
Close enough to share a working day
At only 1 hour and 30 minutes apart, the two working days overlap almost completely. Scheduling is barely constrained by the difference.
Major Cities in Each Zone
Cities on CET
Cities on IRST
Frequently Asked Questions
What is the time difference between CET and IRST?
IRST is 1 hour and 30 minutes ahead of CET. That is the live figure. Taken strictly as written, the gap between CET and IRST is 2 hours and 30 minutes — the two differ because at least one of these regions is currently on daylight saving.
What is 9:00 AM CET in IRST?
9:00 AM CET is 10:30 AM IRST.
What are the best hours to schedule a call between CET and IRST?
Between 9:00 AM and 4:00 PM CET, which is 10:30 AM to 5:30 PM IRST. Both sides are inside normal business hours through that window.
Does the difference between CET and IRST change during the year?
Yes. CET observes daylight saving and IRST does not, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, October 25, 2026.
Does CET always mean Central European Time?
Most of continental Europe moves to CEST (UTC+2) for the summer.
Does IRST always mean Iran Standard Time?
Iran abolished daylight saving in 2022, so the half-hour offset now holds all year.