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).

IRST to Hong Kong

+4h 30m

IRST

IRSTSOURCE

UTC+03:30

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Hong Kong

HKT

Hong Kong · UTC+08:00

HH04

MM30

16:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

IRST

Hong Kong

12:00 AM

4:30 AM

2:00 AM

6:30 AM

4:00 AM

8:30 AM

6:00 AM

10:30 AM

8:00 AM

12:30 PM

10:00 AM

2:30 PM

12:00 PM

4:30 PM

2:00 PM

6:30 PM

4:00 PM

8:30 PM

6:00 PM

10:30 PM

8:00 PM

12:30 AM+1

10:00 PM

2:30 AM+1

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

IRST and HKT on the World Map

The map below highlights the IRST (Iran Standard Time) and HKT (Hong Kong Time) timezone regions across the globe.

IRST Zone

→

HKT 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

HKT – Hong Kong Time

UTC+08:00

Hong Kong Time (HKT, UTC+08:00) is the time zone for Hong Kong, 8 hours ahead of UTC.

Countries in HKT

Hong Kong SAR

Major Cities in HKT

Hong KongKowloonTsuen WanSha Tin

Key Facts about HKT

•Hong Kong does not observe daylight saving time and has kept UTC+08:00 since 1979.
•HKT shares its offset with China Standard Time, Singapore Time and Philippine Time.
•The Hong Kong Stock Exchange opens at 09:30 HKT.
•Hong Kong Time does not change with the seasons, so its gap to other zones is fixed.

Daylight Saving:No – UTC+08:00 year-round

Learn more about HKT on Wikipedia

About Hong Kong

Wikipedia

Hong Kong Time (HKT) is UTC+8 with no daylight saving. As a major financial gateway to China, Hong Kong trading hours overlap with European morning sessions.

Population:7.5 million

Metro:7.5 million

Business Hours:9:00 AM - 6:00 PM HKT

Currency:HKD (HK$)

Stock Exchange:HKEX (Hong Kong Stock Exchange)

Key Landmarks

Victoria PeakTian Tan BuddhaVictoria HarbourStar FerryHong Kong Disneyland

Did You Know?

The city has one of the world's most efficient and affordable public transit systems.

Learn more about HKT timezone →

Time Conversion Guide: IRST to Hong Kong

IRST runs on Iran Standard Time (IRST) at UTC+03:30. Hong Kong runs on Hong Kong Standard Time (HKT) at UTC+08:00. That puts IRST 4 hours 30 minutes ahead of Hong Kong — a difference of +4h 30m at the current offsets.

In practice, when it is 9:00 AM in IRST it is 1:30 PM in Hong Kong. Midnight in IRST is 4:30 AM in Hong Kong. Neither zone observes daylight saving time, so the offset between them stays constant all year.

IRST to Hong Kong time conversion table

IRST (IRST)	Hong Kong (HKT)	Day
12:00 AM	4:30 AM	same day
6:00 AM	10:30 AM	same day
7:00 AM	11:30 AM	same day
8:00 AM	12:30 PM	same day
9:00 AM	1:30 PM	same day
12:00 PM	4:30 PM	same day
3:00 PM	7:30 PM	same day
5:00 PM	9:30 PM	same day
6:00 PM	10:30 PM	same day
9:00 PM	1:30 AM	next day

Why people convert IRST to Hong Kong time

Scheduling a call from IRST to Hong Kong: a 10:00 AM start in IRST lands at 2:30 PM in Hong Kong, so you can confirm the slot without doing the arithmetic yourself.
Finding shared working hours: both IRST and Hong Kong are inside the 9-to-5 working day between 9:00 AM and 12:30 PM IRST time (1:30 PM–5:00 PM HKT). That is roughly 3 hours 30 minutes of usable overlap.
Coordinating a IRST-based team with Hong Kong 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 +4h 30m gap is not.
Block 9:00 AM–12:30 PM IRST as the recurring meeting window if you work primarily from IRST and need Hong Kong colleagues present.

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 HKT (Hong Kong Time)

Hong Kong Time (HKT) is fixed at UTC+08:00 all year and does not observe daylight saving time. Hong Kong last used summer time in 1979 and has kept a single offset since. HKT shares the UTC+08:00 offset with China Standard Time, Singapore Time, Malaysian Time, Philippine Time and Australian Western Standard Time, but is listed separately because Hong Kong maintains its own timekeeping authority. As a major financial centre, Hong Kong's trading hours set the rhythm for markets across Asia, opening at 09:30 HKT which is 01:30 in London and 20:30 the previous evening in New York.

Best time to call between IRST and Hong Kong

Both IRST and Hong Kong sit inside the 9 AM – 5 PM working day between 9:00 AM–12:30 PM IRST, which is 1:30 PM–5:00 PM HKT. That gives roughly 3 hours and 30 minutes of shared time — the safest window for a live call or meeting.

Business hours overlap

IRST and Hong Kong overlap for about 3 hours during the working day — enough for meetings if you avoid the edges of the window.

IRST is 4 hours 30 minutes ahead of Hong Kong (IRST UTC+03:30 → HKT UTC+08:00). The shared working window is 9:00 AM–12:30 PM IRST. 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 Hong Kong?

IRST (IRST, UTC+03:30) is 4 hours 30 minutes ahead of Hong Kong (HKT, UTC+08:00). The gap is currently +4h 30m.

How do I convert IRST time to Hong Kong time?

Add +4h 30m to IRST local time. For example, 9:00 AM in IRST is 1:30 PM in Hong Kong.

What time is it in Hong Kong right now?

Hong Kong uses HKT at UTC+08:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +4h 30m offset from IRST.

What is the best time to call Hong Kong from IRST?

Call between 9:00 AM and 12:30 PM IRST — that maps to 1:30 PM–5:00 PM HKT and keeps both parties inside the working day.

Which is ahead, IRST or Hong Kong?

IRST is 4 hours 30 minutes ahead of Hong Kong. When it is 12:00 PM in IRST it is 4:30 PM in Hong Kong.

Do IRST and Hong Kong use different time zones?

IRST uses IRST at UTC+03:30, while Hong Kong (Hong Kong) uses HKT at UTC+08:00. The IANA identifiers are Asia/Tehran and Asia/Hong_Kong.

Does daylight saving time affect the IRST–Hong Kong difference?

Neither zone observes daylight saving time, so the +4h 30m offset between IRST and Hong Kong is fixed all year.

Which other cities share IRST's time zone?

IRST also covers Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.

Which countries use IRST, IRST's zone?

IRST is used in Iran.

Is there a day difference between IRST and Hong Kong?

Not normally. The +4h 30m gap only pushes the date over for late-evening times.

What is the time difference between IRST and Hong Kong?

Hong Kong is +4h 30m from IRST.

What timezone is IRST in?

IRST operates on its local timezone.

What timezone is Hong Kong in?

Hong Kong Time (HKT) is UTC+8 with no daylight saving. As a major financial gateway to China, Hong Kong trading hours overlap with European morning sessions.

What are the business hours in Hong Kong?

Standard business hours in Hong Kong are 9:00 AM - 6:00 PM HKT.

Which countries use IRST (Iran Standard Time)?

IRST is used in Iran.

Does IRST observe daylight saving time?

Yes, IRST switches to IRDT during summer months.

What are some interesting 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).

Which cities are in the HKT timezone?

Major cities in the HKT timezone include Hong Kong, Kowloon, Tsuen Wan, Sha Tin.

What is the UTC offset for HKT?

Hong Kong Time (HKT) is at UTC+08:00.

What should I know about the HKT timezone?

Hong Kong does not observe daylight saving time and has kept UTC+08:00 since 1979. HKT shares its offset with China Standard Time, Singapore Time and Philippine Time.