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).

Ho Chi Minh to IRST

-3h 30m

Ho Chi Minh

ICTSOURCE

Vietnam · UTC+07:00

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

IRST

UTC+03:30

HH08

MM30

08:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

Ho Chi Minh

IRST

12:00 AM

8:30 PM-1

2:00 AM

10:30 PM-1

4:00 AM

12:30 AM

6:00 AM

2:30 AM

8:00 AM

4:30 AM

10:00 AM

6:30 AM

12:00 PM

8:30 AM

2:00 PM

10:30 AM

4:00 PM

12:30 PM

6:00 PM

2:30 PM

8:00 PM

4:30 PM

10:00 PM

6:30 PM

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

ICT and IRST on the World Map

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

ICT Zone

→

IRST Zone

Explore all world timezones interactively →

ICT – Indochina Time

UTC+07:00

Indochina Time (ICT) is the time zone for Vietnam, Thailand, Laos, and Cambodia, 7 hours ahead of UTC.

Countries in ICT

ThailandVietnamCambodiaLaosIndonesia (WIB)

Major Cities in ICT

BangkokHo Chi Minh CityHanoiJakartaPhnom PenhVientiane

Key Facts about ICT

•Bangkok is one of the most visited cities in the world.
•ICT is 12 hours ahead of EST.
•Thailand, Vietnam, and Cambodia all share ICT.

Daylight Saving:No – UTC+07:00 year-round

Learn more about ICT on Wikipedia

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

About Ho Chi Minh

Wikipedia

Ho Chi Minh City operates on Indochina Time (ICT), UTC+7. As Vietnam's economic powerhouse and a manufacturing hub, Saigon drives Southeast Asian trade.

Population:9 million

Metro:13 million

Business Hours:8:00 AM - 5:00 PM ICT

Currency:VND (₫)

Stock Exchange:HOSE (Ho Chi Minh Stock Exchange)

Key Landmarks

Notre-Dame CathedralWar Remnants MuseumBen Thanh MarketIndependence PalaceCu Chi Tunnels

Did You Know?

The city has over 5 million motorbikes, outnumbering cars significantly.

Learn more about ICT timezone →

Ho Chi Minh to IRST Time Difference – Complete Guide

Ho Chi Minh runs on Indochina Time (ICT) at UTC+07:00. IRST runs on Iran Standard Time (IRST) at UTC+03:30. That puts Ho Chi Minh 3 hours 30 minutes behind IRST — a difference of -3h 30m at the current offsets.

In practice, when it is 9:00 AM in Ho Chi Minh it is 5:30 AM in IRST. Midnight in Ho Chi Minh is 8:30 PM in IRST. Neither zone observes daylight saving time, so the offset between them stays constant all year.

Ho Chi Minh to IRST time conversion table

Ho Chi Minh (ICT)	IRST (IRST)	Day
12:00 AM	8:30 PM	previous day
6:00 AM	2:30 AM	same day
7:00 AM	3:30 AM	same day
8:00 AM	4:30 AM	same day
9:00 AM	5:30 AM	same day
12:00 PM	8:30 AM	same day
3:00 PM	11:30 AM	same day
5:00 PM	1:30 PM	same day
6:00 PM	2:30 PM	same day
9:00 PM	5:30 PM	same day

Why people convert Ho Chi Minh to IRST time

Scheduling a call from Ho Chi Minh to IRST: a 10:00 AM start in Ho Chi Minh lands at 6:30 AM in IRST, so you can confirm the slot without doing the arithmetic yourself.
Finding shared working hours: both Ho Chi Minh and IRST are inside the 9-to-5 working day between 12:30 PM and 5:00 PM ICT time (9:00 AM–1:30 PM IRST). That is roughly 4 hours 30 minutes of usable overlap.
Coordinating a Ho Chi Minh-based team with IRST 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 ICT" is unambiguous; "3 PM" across a -3h 30m gap is not.
Block 12:30 PM–5:00 PM ICT as the recurring meeting window if you work primarily from Ho Chi Minh and need IRST colleagues present.

About ICT (Indochina Time)

Indochina Time (ICT) is used across Southeast Asia including Vietnam, Thailand, Laos, and Cambodia. Indonesia (Western time, WIB) also uses UTC+07:00. ICT does not observe daylight saving time.

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.

Best time to call between Ho Chi Minh and IRST

Both Ho Chi Minh and IRST sit inside the 9 AM – 5 PM working day between 12:30 PM–5:00 PM ICT, which is 9:00 AM–1:30 PM IRST. That gives roughly 4 hours and 30 minutes of shared time — the safest window for a live call or meeting.

Business hours overlap

Ho Chi Minh and IRST overlap for about 4 hours during the working day — enough for meetings if you avoid the edges of the window.

Ho Chi Minh is 3 hours 30 minutes behind IRST (ICT UTC+07:00 → IRST UTC+03:30). The shared working window is 12:30 PM–5:00 PM ICT. 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 Ho Chi Minh and IRST?

Ho Chi Minh (ICT, UTC+07:00) is 3 hours 30 minutes behind IRST (IRST, UTC+03:30). The gap is currently -3h 30m.

How do I convert Ho Chi Minh time to IRST time?

Add -3h 30m to Ho Chi Minh local time. For example, 9:00 AM in Ho Chi Minh is 5:30 AM in IRST.

What time is it in IRST right now?

IRST uses IRST at UTC+03:30. Use the live converter at the top of this page — it updates in real time and already accounts for the -3h 30m offset from Ho Chi Minh.

What is the best time to call IRST from Ho Chi Minh?

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

Which is behind, Ho Chi Minh or IRST?

Ho Chi Minh is 3 hours 30 minutes behind IRST. When it is 12:00 PM in Ho Chi Minh it is 8:30 AM in IRST.

Do Ho Chi Minh and IRST use different time zones?

Ho Chi Minh (Vietnam) uses ICT at UTC+07:00, while IRST uses IRST at UTC+03:30. The IANA identifiers are Asia/Ho_Chi_Minh and Asia/Tehran.

Does daylight saving time affect the Ho Chi Minh–IRST difference?

Neither zone observes daylight saving time, so the -3h 30m offset between Ho Chi Minh and IRST is fixed all year.

Which other cities share Ho Chi Minh's time zone?

ICT also covers Bangkok, Ho Chi Minh City, Hanoi, Jakarta, Phnom Penh, Vientiane.

Which countries use ICT, Ho Chi Minh's zone?

ICT is used in Thailand, Vietnam, Cambodia, Laos, Indonesia (WIB).

Is there a day difference between Ho Chi Minh and IRST?

Not normally. The -3h 30m gap only pushes the date over the previous day.

What is the time difference between Ho Chi Minh and IRST?

IRST is -3h 30m from Ho Chi Minh.

What timezone is Ho Chi Minh in?

Ho Chi Minh City operates on Indochina Time (ICT), UTC+7. As Vietnam's economic powerhouse and a manufacturing hub, Saigon drives Southeast Asian trade.

What timezone is IRST in?

IRST operates on its local timezone.

What are the business hours in Ho Chi Minh?

Standard business hours in Ho Chi Minh are 8:00 AM - 5:00 PM ICT.

Which countries use ICT (Indochina Time)?

ICT is used in Thailand, Vietnam, Cambodia, Laos, Indonesia (WIB).

Does ICT observe daylight saving time?

No, ICT does not observe daylight saving time and remains at UTC+07:00 year-round.

What are some interesting facts about ICT?

Bangkok is one of the most visited cities in the world. ICT is 12 hours ahead of EST.

Which cities are in the IRST timezone?

Major cities in the IRST timezone include Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.

What is the UTC offset for IRST?

Iran Standard Time (IRST) is at UTC+03:30. During daylight saving time, it shifts to IRDT.

What should I know about the IRST timezone?

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).

When is it midnight in Ho Chi Minh, what time is it in IRST?

When it is 12:00 AM (midnight) in Ho Chi Minh (ICT), it is -3h 30m later in IRST (IRST).

Related Developer Tools

Explore more tools that work great with timezone conversions for international teams:

Unix Timestamp Converter

Convert timestamps to dates across timezones

Date Converter

Convert dates between different formats

Cron Expression Generator

Schedule tasks across different timezones

World Timezone Explorer

Interactive map of all world timezones

Date Calculator

Calculate date differences and durations

Word Counter

Count words for international content

Related Timezone Conversions

ho chi minh→tokyo ho chi minh→vietnam ho chi minh→new york ho chi minh→london irst→tehran irst→iran irst→new york irst→london

More Ho Chi Minh time conversions

See every conversion from Ho Chi Minh →·See every conversion from IRST →

View all timezone conversions →