What is the time difference between IST and IRST?

Iran Standard Time (IRST) is 2 hours behind India Standard Time (IST). IST uses a UTC offset of UTC+5:30, while IRST uses UTC+3:30. For example, when it's 9:00 AM in IST, it's 7:00 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 IST to IRST?

To convert IST to IRST, subtract 2 hours from the IST time. For example, 9:00 AM IST is 7:00 AM IRST, and 5:00 PM IST is 3:00 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 IST?

When it's 12:00 PM (noon) in IST, it's 10:00 AM in IRST. This is because IRST is 2 hours behind IST. Similarly, when it's 6:00 PM in IST, it's 4:00 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 IST?

IRST is 2 hours behind IST. This means when it's 9:00 AM in IST, it's 7:00 AM in IRST, and when it's midnight in IST, it's 10:00 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 IST?

IRST is behind IST by 2 hours. Clocks in IRST show an earlier time than IST, meaning the day starts later in IRST relative to IST. For example, when it's noon in IST, it's still 10:00 AM in IRST. This difference stays the same year-round.

Does IST observe daylight saving time?

No, India Standard Time does not observe daylight saving time. The UTC offset of UTC+5:30 remains the same year-round, making time conversions from IST 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 IST to IRST?

The best time for a call between IST 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 11:00 AM and 7:00 PM your IST time. Avoid calling too early or late, as the 2 hours 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 IST and IRST ever have the same time?

No, IST and IRST are always 2 hours 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 2 hours 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.

IST to IRST Converter

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

Timezone Details

India Standard Time

8:40 AM

Friday, April 3, 2026

IST (UTC+05:30)

Tehran

6:40 AM

Friday, April 3, 2026

Tehran (UTC+03:30)

Difference: -2 hours

IST DST: No

24-Hour Overview

IST — 24-hour overview

12a12a

3a3a

6a6a

9a9a

10a

11a

12p12p

3p3p

6p6p

9p9p

10p

11p

NightMorningBusinessEvening

Tehran — 24-hour overview

10p10p

11p

12a

1a1a

4a4a

7a7a

10a10a

11a

12p

1p1p

4p4p

7p7p

NightMorningBusinessEvening

Frequently Asked Questions

Related Conversions

IRST to IST EST to IST IST to EST PST to IST IST to PST GMT to IST IST to GMT IST to JST JST to IST

Cities in These Timezones

IST Cities

Delhi Mumbai Kolkata Bangalore Chennai

IRST Cities

Tehran

More Tools

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

Learn More

How Time Zones Work Understanding DST Timezone Abbreviations

External Resources

India Standard Time on Wikipedia IANA Time Zone Database