Does it handle Daylight Saving Time?

Yes, the tool automatically adjusts for Daylight Saving Time based on the specific date you select, ensuring accurate conversions year-round.

Can I add multiple cities?

Yes, you can add as many cities as you need to the dashboard to compare times across your entire global network simultaneously.

IRST to HST

-13h 30m

IRST

IRSTSOURCE

UTC+03:30

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

HST

UTC-10:00

HH10

MM30

(previous day)22:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

IRST

HST

12:00 AM

10:30 AM-1

2:00 AM

12:30 PM-1

4:00 AM

2:30 PM-1

6:00 AM

4:30 PM-1

8:00 AM

6:30 PM-1

10:00 AM

8:30 PM-1

12:00 PM

10:30 PM-1

2:00 PM

12:30 AM

4:00 PM

2:30 AM

6:00 PM

4:30 AM

8:00 PM

6:30 AM

10:00 PM

8:30 AM

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

IRST and HST on the World Map

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

IRST Zone

→

HST Zone

Explore all world timezones interactively →

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

HST – Hawaii Standard Time

UTC-10:00

Hawaii Standard Time (HST) is the time zone for the Hawaiian Islands, 10 hours behind UTC.

Countries in HST

United States (Hawaii)

Major Cities in HST

HonoluluHiloKailuaPearl CityKapolei

Key Facts about HST

•Hawaii does not observe daylight saving time.
•HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
•Hawaii is one of only two US states that don't observe DST (the other is Arizona).

Daylight Saving:No – UTC-10:00 year-round

Learn more about HST on Wikipedia

Everything You Need to Know About IRST and HST Time

IRST runs on Iran Standard Time (IRST) at UTC+03:30. HST runs on Hawaii Standard Time (HST) at UTC-10:00. That puts IRST 13 hours 30 minutes behind HST — a difference of -13h 30m at the current offsets.

In practice, when it is 9:00 AM in IRST it is 7:30 PM in HST on the previous day. Midnight in IRST is 10:30 AM in HST. Neither zone observes daylight saving time, so the offset between them stays constant all year.

IRST to HST time conversion table

IRST (IRST)	HST (HST)	Day
12:00 AM	10:30 AM	previous day
6:00 AM	4:30 PM	previous day
7:00 AM	5:30 PM	previous day
8:00 AM	6:30 PM	previous day
9:00 AM	7:30 PM	previous day
12:00 PM	10:30 PM	previous day
3:00 PM	1:30 AM	same day
5:00 PM	3:30 AM	same day
6:00 PM	4:30 AM	same day
9:00 PM	7:30 AM	same day

Why people convert IRST to HST time

Scheduling a call from IRST to HST: a 10:00 AM start in IRST lands at 8:30 PM in HST the previous day, so you can confirm the slot without doing the arithmetic yourself.
Handling a -13h 30m gap: IRST and HST have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in HST is 7:30 PM in IRST.
Coordinating a IRST-based team with HST contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.

Always state the zone abbreviation, not just the hour. "3:00 PM IRST" is unambiguous; "3 PM" across a -13h 30m gap is not.
With a -13h 30m gap there is no shared 9-to-5 window, so alternate the early start: one week IRST takes the early slot, the next week HST does.

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.

About HST (Hawaii Standard Time)

Hawaii Standard Time (HST) is used in the state of Hawaii and does not observe daylight saving time. This makes HST one of the most consistent time zones in the US. The Hawaiian Islands are among the last places on Earth to see a new calendar day.

Best time to call between IRST and HST

With a -13h 30m offset there is no overlap inside a normal 9 AM – 5 PM day. HST opens at 9:00 AM HST, which is 7:30 PM in IRST, so real-time calls need an early-morning or late-evening slot on one side.

Business hours overlap

IRST and HST have no shared working hours because of the -13h 30m gap. Teams need to alternate early starts or rely on asynchronous handovers.

IRST is 13 hours 30 minutes behind HST (IRST UTC+03:30 → HST UTC-10:00). There is no shared 9-to-5 window, so plan around an early or late slot. 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 IRST and HST?

IRST (IRST, UTC+03:30) is 13 hours 30 minutes behind HST (HST, UTC-10:00). The gap is currently -13h 30m.

How do I convert IRST time to HST time?

Add -13h 30m to IRST local time. For example, 9:00 AM in IRST is 7:30 PM in HST (previous day).

What time is it in HST right now?

HST uses HST at UTC-10:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -13h 30m offset from IRST.