Does it account for Daylight Saving Time?

Yes, our converter uses the IANA timezone database, which includes all current DST rules for every timezone in the world.

UTC (Coordinated Universal Time) is the primary time standard by which the world regulates clocks. All timezones are defined as offsets from UTC.

Can I compare multiple timezones at once?

Yes, you can add multiple cities or timezones and see the equivalent times side by side.

How many timezones are there in the world?

There are 38 distinct UTC offsets in use, ranging from UTC-12 to UTC+14. This includes half-hour (UTC+5:30 India, UTC+9:30 Australia) and 45-minute offsets (UTC+5:45 Nepal, UTC+8:45 Australia).

What is the International Date Line?

The International Date Line (IDL) runs roughly along the 180° meridian in the Pacific Ocean. When you cross it westward, you gain a day; crossing eastward, you lose a day.

Why do some timezones have 30 or 45 minute offsets?

Countries chose offsets that best matched their solar noon. India uses UTC+5:30 and Nepal uses UTC+5:45 because standard hourly offsets didn't align well with their geography.

Which country has the most timezones?

France has the most (12 timezones) due to overseas territories. Russia spans 11 timezones. The US has 6 (including Hawaii and Alaska).

GST to Iran

-0h 30m

GST

GSTSOURCE

UTC+04:00

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Iran

IRST

UTC+03:30

HH11

MM30

11:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

GST

Iran

12:00 AM

11:30 PM-1

2:00 AM

1:30 AM

4:00 AM

3:30 AM

6:00 AM

5:30 AM

8:00 AM

7:30 AM

10:00 AM

9:30 AM

12:00 PM

11:30 AM

2:00 PM

1:30 PM

4:00 PM

3:30 PM

6:00 PM

5:30 PM

8:00 PM

7:30 PM

10:00 PM

9:30 PM

Green rows indicate typical business hours (9 AM - 5 PM)

GST and IRST on the World Map

The map below highlights the GST (Gulf Standard Time) and IRST (Iran Standard Time) timezone regions across the globe.

GST Zone

→

IRST Zone

Explore all world timezones interactively →

GST – Gulf Standard Time

UTC+04:00

Gulf Standard Time (GST) is used in the UAE, Oman, and other Gulf states, 4 hours ahead of UTC.

Countries in GST

UAEOmanGeorgiaAzerbaijanMauritius

Major Cities in GST

DubaiAbu DhabiMuscatBakuTbilisi

Key Facts about GST

•Dubai uses GST year-round with no daylight saving time.
•GST is 9 hours ahead of EST and 4 hours ahead of GMT.
•The Dubai Financial Market (DFM) operates on GST.

Daylight Saving:No – UTC+04:00 year-round

Learn more about GST on Wikipedia

IRST – Iran Standard Time

UTC+03:30

Iran Standard Time (IRST) is the time zone for Iran, 3 hours and 30 minutes ahead of UTC.

Countries in IRST

Iran

Major Cities in IRST

TehranIsfahanMashhadTabrizShirazKaraj

Key Facts about IRST

•IRST is one of only a few time zones with a 30-minute offset.
•Iran observes daylight saving time, switching to IRDT (UTC+04:30).
•Tehran has a metropolitan population of over 16 million.

Daylight Saving:Yes – switches to IRDT

Learn more about IRST on Wikipedia

GST vs Iran: Offsets, DST and Best Call Times

GST runs on Gulf Standard Time (GST) at UTC+04:00. Iran runs on Iran Standard Time (IRST) at UTC+03:30. That puts GST 30 minutes behind Iran — a difference of -0h 30m at the current offsets.

In practice, when it is 9:00 AM in GST it is 8:30 AM in Iran. Midnight in GST is 11:30 PM in Iran. Neither zone observes daylight saving time, so the offset between them stays constant all year.

GST to Iran time conversion table

GST (GST)	Iran (IRST)	Day
12:00 AM	11:30 PM	previous day
6:00 AM	5:30 AM	same day
7:00 AM	6:30 AM	same day
8:00 AM	7:30 AM	same day
9:00 AM	8:30 AM	same day
12:00 PM	11:30 AM	same day
3:00 PM	2:30 PM	same day
5:00 PM	4:30 PM	same day
6:00 PM	5:30 PM	same day
9:00 PM	8:30 PM	same day

Why people convert GST to Iran time

Scheduling a call from GST to Iran: a 10:00 AM start in GST lands at 9:30 AM in Iran, so you can confirm the slot without doing the arithmetic yourself.
Finding shared working hours: both GST and Iran are inside the 9-to-5 working day between 9:30 AM and 5:00 PM GST time (9:00 AM–4:30 PM IRST). That is roughly 7 hours 30 minutes of usable overlap.
Keeping family and friends in sync: knowing that 8:00 PM in GST is 7:30 PM in Iran makes it easy to avoid calling at 3 AM.

Always state the zone abbreviation, not just the hour. "3:00 PM GST" is unambiguous; "3 PM" across a -0h 30m gap is not.
Block 9:30 AM–5:00 PM GST as the recurring meeting window if you work primarily from GST and need Iran colleagues present.

About GST (Gulf Standard Time)

Gulf Standard Time (GST) is the time zone used in the United Arab Emirates, Oman, and other Gulf states. GST does not observe daylight saving time. Dubai and Abu Dhabi, major international business and tourism hubs, operate on GST.

About IRST (Iran Standard Time)

Iran Standard Time (IRST) is one of the few time zones with a 30-minute offset. Iran observes daylight saving time (IRDT, UTC+04:30) from late March to late September. Tehran, the capital, is one of the largest cities in the Middle East.

Best time to call between GST and Iran

Both GST and Iran sit inside the 9 AM – 5 PM working day between 9:30 AM–5:00 PM GST, which is 9:00 AM–4:30 PM IRST. That gives roughly 7 hours and 30 minutes of shared time — the safest window for a live call or meeting.

Business hours overlap

GST and Iran share 7 hours of working-hours overlap (9:30 AM–5:00 PM GST), so scheduling a live meeting is straightforward.

GST is 30 minutes behind Iran (GST UTC+04:00 → IRST UTC+03:30). The shared working window is 9:30 AM–5:00 PM GST. Remember to re-check around daylight-saving transitions.

Learn More About Time

Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:

⏳

History of Timekeeping

From sundials to atomic clocks - 5000 years of measuring time

🌍

How Time Zones Work

UTC, offsets, and why zones don't follow straight lines

☀️

Daylight Saving Time

DST dates, which countries observe it, and the ongoing debate

Frequently Asked Questions

What is the time difference between GST and Iran?

GST (GST, UTC+04:00) is 30 minutes behind Iran (IRST, UTC+03:30). The gap is currently -0h 30m.

How do I convert GST time to Iran time?

Add -0h 30m to GST local time. For example, 9:00 AM in GST is 8:30 AM in Iran.

What time is it in Iran right now?

Iran uses IRST at UTC+03:30. Use the live converter at the top of this page — it updates in real time and already accounts for the -0h 30m offset from GST.