What is the time difference between IRST and HST?

Hawaii Standard Time (HST) is 13 hours and 30 minutes behind Iran Standard Time (IRST). IRST uses a UTC offset of UTC+3:30, while HST uses UTC-10. For example, when it's 9:00 AM in IRST, it's 7:30 PM in HST. 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 IRST to HST?

To convert IRST to HST, subtract 13 hours and 30 minutes from the IRST time. For example, 9:00 AM IRST is 7:30 PM HST, and 5:00 PM IRST is 3:30 AM HST. 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 HST when it's noon in IRST?

When it's 12:00 PM (noon) in IRST, it's 10:30 PM in HST. This is because HST is 13 hours and 30 minutes behind IRST. Similarly, when it's 6:00 PM in IRST, it's 4:30 AM in HST. 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 HST from IRST?

HST is 13 hours and 30 minutes behind IRST. This means when it's 9:00 AM in IRST, it's 7:30 PM in HST, and when it's midnight in IRST, it's 10:30 AM in HST. 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 HST ahead or behind IRST?

HST is behind IRST by 13 hours and 30 minutes. Clocks in HST show an earlier time than IRST, meaning the day starts later in HST relative to IRST. For example, when it's noon in IRST, it's still 10:30 PM in HST. This difference stays the same year-round.

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.

Does HST observe daylight saving time?

No, Hawaii Standard Time does not observe daylight saving time. The UTC offset of UTC-10 remains the same year-round, making time conversions to HST more predictable. Countries and regions in this timezone keep their clocks unchanged regardless of the season.

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

The best time for a call between IRST and HST is during overlapping business hours (9 AM – 5 PM) in both timezones. To reach someone in HST during their work day, call between 10:30 PM and 6:30 AM your IRST time. Avoid calling too early or late, as the 13 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 IRST and HST ever have the same time?

No, IRST and HST are always 13 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 13 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.

IRST to HST Converter

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

Timezone Details

Tehran

8:43 AM

Friday, April 3, 2026

Tehran (UTC+03:30)

Hawaii Standard Time

7:13 PM

Thursday, April 2, 2026

HST (UTC-10:00)

Difference: -13h 30m

HST DST: No

24-Hour Overview

Tehran — 24-hour overview

12a12a

3a3a

6a6a

9a9a

10a

11a

12p12p

3p3p

6p6p

9p9p

10p

11p

NightMorningBusinessEvening

HST — 24-hour overview

10a10a

11a

12p

1p1p

4p4p

7p7p

10p10p

11p

12a

1a1a

4a4a

7a7a

NightMorningBusinessEvening

Frequently Asked Questions

Related Conversions

HST to IRST

Cities in These Timezones

IRST Cities

Tehran

HST Cities

Honolulu

More Tools

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

Learn More

How Time Zones Work Understanding DST Timezone Abbreviations

External Resources

Hawaii Standard Time on Wikipedia IANA Time Zone Database