Convert GST to IRST
IRST is 30 minutes behind GST. GST is UTC+4 and IRST is UTC+3:30.
Right now: GST · IRST
Best time to schedule a meeting
Standard 9–5 working hours overlap for 7 hours: 10:00 AM–5:00 PM GST (9:00 AM–4:00 PM IRST). Schedule meetings inside that window.
| GST | IRST | Suitable? |
|---|---|---|
| 9:00 AM | 8:30 AM | outside 9–5 |
| 10:00 AM | 9:30 AM | working hours |
| 11:00 AM | 10:30 AM | working hours |
| 12:00 PM | 11:30 AM | working hours |
| 1:00 PM | 12:30 PM | working hours |
| 2:00 PM | 1:30 PM | working hours |
| 3:00 PM | 2:30 PM | working hours |
| 4:00 PM | 3:30 PM | working hours |
| 5:00 PM | 4:30 PM | working hours |
GST to IRST conversion table
| GST | IRST |
|---|---|
| 12:00 AM | 11:30 PM (previous day) |
| 1:00 AM | 12:30 AM |
| 2:00 AM | 1:30 AM |
| 3:00 AM | 2:30 AM |
| 4:00 AM | 3:30 AM |
| 5:00 AM | 4:30 AM |
| 6:00 AM | 5:30 AM |
| 7:00 AM | 6:30 AM |
| 8:00 AM | 7:30 AM |
| 9:00 AM | 8:30 AM |
| 10:00 AM | 9:30 AM |
| 11:00 AM | 10:30 AM |
| 12:00 PM | 11:30 AM |
| 1:00 PM | 12:30 PM |
| 2:00 PM | 1:30 PM |
| 3:00 PM | 2:30 PM |
| 4:00 PM | 3:30 PM |
| 5:00 PM | 4:30 PM |
| 6:00 PM | 5:30 PM |
| 7:00 PM | 6:30 PM |
| 8:00 PM | 7:30 PM |
| 9:00 PM | 8:30 PM |
| 10:00 PM | 9:30 PM |
| 11:00 PM | 10:30 PM |
About GST
Gulf Standard Time (GST) is UTC+4. It is used in Dubai, Abu Dhabi and Muscat.
Gulf Standard Time is UTC+4, covering the United Arab Emirates and Oman, and there is no daylight saving anywhere on the Arabian peninsula. The scheduling complication in the region is not the clock but the week: the UAE moved its weekend to Saturday–Sunday in 2022, while Saudi Arabia and several neighbours keep Friday–Saturday, so a Thursday afternoon meeting lands differently across a border that has no time difference at all.
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?
Neither GST nor IRST shifts with the seasons, so this 0.5-hour difference holds all year. That is unusual enough to be worth relying on: most cross-continental gaps move twice a year.
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 GST in IRST?
9:00 AM GST is 8:30 AM IRST.
Is IRST ahead of GST?
IRST is 30 minutes behind GST.
Which time zone does this use?
GST is UTC+4 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.