What is the time difference between GST and IRST?

Iran Standard Time (IRST) is 0 hours and 30 minutes behind Gulf Standard Time (GST). GST uses a UTC offset of UTC+4, while IRST uses UTC+3:30. For example, when it's 9:00 AM in GST, it's 8:30 AM in IRST. This difference remains constant year-round since neither timezone observes daylight saving time. Use the conversion table above to see the exact time for each hour of the day.

How do I convert GST to IRST?

To convert GST to IRST, subtract 0 hours and 30 minutes from the GST time. For example, 9:00 AM GST is 8:30 AM IRST, and 5:00 PM GST is 4:30 PM IRST. Since neither timezone observes DST, this conversion stays the same all year. You can also use the interactive converter above for quick, accurate results.

What time is it in IRST when it's noon in GST?

When it's 12:00 PM (noon) in GST, it's 11:30 AM in IRST. This is because IRST is 0 hours and 30 minutes behind GST. Similarly, when it's 6:00 PM in GST, it's 5:30 PM in IRST. This relationship is constant throughout the year. The color-coded conversion table above shows every hour mapped between both timezones.

How many hours behind is IRST from GST?

IRST is 0 hours and 30 minutes behind GST. This means when it's 9:00 AM in GST, it's 8:30 AM in IRST, and when it's midnight in GST, it's 11:30 PM in IRST. This offset is constant throughout the year since neither timezone uses daylight saving time. The conversion table above provides a complete hour-by-hour mapping.

Is IRST ahead or behind GST?

IRST is behind GST by 0 hours and 30 minutes. Clocks in IRST show an earlier time than GST, meaning the day starts later in IRST relative to GST. For example, when it's noon in GST, it's still 11:30 AM in IRST. This difference stays the same year-round.

Does GST observe daylight saving time?

No, Gulf Standard Time does not observe daylight saving time. The UTC offset of UTC+4 remains the same year-round, making time conversions from GST more predictable. Countries and regions in this timezone keep their clocks unchanged regardless of the season.

Does IRST observe daylight saving time?

No, Iran Standard Time does not observe daylight saving time. The UTC offset of UTC+3:30 remains the same year-round, which simplifies time conversions. Regions using IRST keep their clocks unchanged regardless of the season.

What is the best time to call from GST to IRST?

The best time for a call between GST and IRST is during overlapping business hours (9 AM – 5 PM) in both timezones. To reach someone in IRST during their work day, call between 9:30 AM and 5:30 PM your GST time. Avoid calling too early or late, as the 0 hours and 30 minutes difference means your evening could be their early morning. Check the color-coded conversion table above — green hours indicate business hours in both zones, making it easy to find the ideal time.

Do GST and IRST ever have the same time?

No, GST and IRST are always 0 hours and 30 minutes apart and never display the same clock time simultaneously. Neither timezone observes DST, so the difference is constant year-round with no seasonal variation. The 0 hours and 30 minutes offset is determined by their fixed positions relative to the Prime Meridian (UTC). You can always rely on this consistent difference when planning across these timezones.

GST to IRST Converter

Convert Gulf Standard Time to Iran Standard Time. See the hour-by-hour conversion table below.

Timezone Details

Gulf Standard Time

10:37 PM

Thursday, April 2, 2026

GST (UTC+04:00)

Tehran

10:07 PM

Thursday, April 2, 2026

Tehran (UTC+03:30)

Difference: -0h 30m

GST DST: No

24-Hour Overview

GST — 24-hour overview

12a12a

3a3a

6a6a

9a9a

10a

11a

12p12p

3p3p

6p6p

9p9p

10p

11p

NightMorningBusinessEvening

Tehran — 24-hour overview

11p11p

12a

2a2a

5a5a

8a8a

10a

11a11a

12p

2p2p

5p5p

8p8p

10p

NightMorningBusinessEvening

Frequently Asked Questions

Related Conversions

IRST to GST

Cities in These Timezones

GST Cities

Dubai Abu Dhabi

IRST Cities

Tehran

More Tools

Compare GST & IRST Plan a Meeting (GST & IRST)See on Map

Learn More

How Time Zones Work Understanding DST Timezone Abbreviations

External Resources

Gulf Standard Time on Wikipedia IANA Time Zone Database