Convert CEST to IRST
IRST is 1 hour 30 minutes ahead of CEST. CEST is UTC+2 and IRST is UTC+3:30.
Right now: CEST · IRST
Best time to schedule a meeting
Standard 9–5 working hours overlap for 7 hours: 9:00 AM–4:00 PM CEST (10:00 AM–5:00 PM IRST). Schedule meetings inside that window.
| CEST | IRST | Suitable? |
|---|---|---|
| 9:00 AM | 10:30 AM | working hours |
| 10:00 AM | 11:30 AM | working hours |
| 11:00 AM | 12:30 PM | working hours |
| 12:00 PM | 1:30 PM | working hours |
| 1:00 PM | 2:30 PM | working hours |
| 2:00 PM | 3:30 PM | working hours |
| 3:00 PM | 4:30 PM | working hours |
| 4:00 PM | 5:30 PM | outside 9–5 |
| 5:00 PM | 6:30 PM | outside 9–5 |
CEST to IRST conversion table
| CEST | IRST |
|---|---|
| 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 |
| 9:00 AM | 10:30 AM |
| 10:00 AM | 11:30 AM |
| 11:00 AM | 12:30 PM |
| 12:00 PM | 1:30 PM |
| 1:00 PM | 2:30 PM |
| 2:00 PM | 3:30 PM |
| 3:00 PM | 4:30 PM |
| 4:00 PM | 5:30 PM |
| 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) |
About CEST
Central European Summer Time (CEST) is UTC+2. It is used in Paris, Berlin, Madrid and Rome from late March to late October.
Central European Summer Time is UTC+2, in force from the last Sunday in March to the last Sunday in October. The European changeover happens at 01:00 UTC everywhere simultaneously, unlike the US which changes at 2am local time in each zone — so Europe's internal offsets never break during the transition, while North America's briefly do.
About IRST
Iran Standard Time (IRST) is UTC+3:30. It is used in Iran, all year.
Iran Standard Time is UTC+3:30. Iran ran daylight saving for decades and stopped in 2022, so material written before then puts the country half an hour further ahead in summer and is now wrong. Half-hour offsets are rare enough that scheduling tools sometimes round them, which turns a correct calculation into a thirty-minute error.
Does this gap change with the seasons?
This gap is seasonal. The abbreviations themselves are fixed offsets, but the region on CEST switches to CET (UTC+1) from late October to late March. So the 1.5-hour figure on this page is correct for the part of the year when both places are actually on these abbreviations, and changes by an hour outside it.
IRST does not shift, so the whole change comes from one side. A recurring meeting fixed in IRST will appear to move by an hour for everyone on the other side, twice a year, without anyone changing anything.
This is the reason scheduling systems store an IANA zone such as Region/City rather than an offset or an abbreviation: the zone knows its own rules and the offset does not.
Frequently asked questions
What time is 9:00 AM CEST in IRST?
9:00 AM CEST is 10:30 AM IRST.
Is IRST ahead of CEST?
IRST is 1 hour 30 minutes ahead of CEST.
Which time zone does this use?
CEST is UTC+2 and IRST is UTC+3:30. Both abbreviations denote a single fixed offset, so this conversion never shifts with daylight saving — what changes is which abbreviation a place is using at the time.