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 Dublin

-2h 30m

IRST

IRSTSOURCE

UTC+03:30

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Dublin

IST

Ireland · UTC+01:00☀ DST active

HH09

MM30

09:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

IRST

Dublin

12:00 AM

9:30 PM-1

2:00 AM

11:30 PM-1

4:00 AM

1:30 AM

6:00 AM

3:30 AM

8:00 AM

5:30 AM

10:00 AM

7:30 AM

12:00 PM

9:30 AM

2:00 PM

11:30 AM

4:00 PM

1:30 PM

6:00 PM

3:30 PM

8:00 PM

5:30 PM

10:00 PM

7:30 PM

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

IRST and IST on the World Map

The map below highlights the IRST (Iran Standard Time) and IST (Greenwich Mean Time) timezone regions across the globe.

IRST Zone

→

IST 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

GMT – Greenwich Mean Time

UTC+00:00

Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London. It is the same as UTC+00:00.

Countries in GMT

United KingdomIrelandIcelandPortugal (mainland)GhanaSenegalMaliMauritaniaGambiaGuineaSierra LeoneLiberiaIvory CoastBurkina FasoMorocco (historically)

Major Cities in GMT

LondonDublinLisbonAccraReykjavikEdinburghCasablancaDakarBamakoAbidjanConakryFreetownMonrovia

Key Facts about GMT

•GMT is based on the Prime Meridian (0° longitude) passing through Greenwich, London.
•The Royal Observatory in Greenwich has been the reference point for GMT since 1884.
•GMT and UTC are often used interchangeably, but UTC is based on atomic clocks.
•Iceland uses GMT year-round and never observes daylight saving time.
•The UK switches from GMT to BST (British Summer Time) in late March each year.

Daylight Saving:Yes – switches to BST

Learn more about GMT on Wikipedia

Understanding the -2h 30m Gap: IRST vs Dublin

IRST runs on Iran Standard Time (IRST) at UTC+03:30. Dublin runs on Irish Standard Time (IST) at UTC+01:00, also currently on daylight saving time. That puts IRST 2 hours 30 minutes behind Dublin — a difference of -2h 30m at the current offsets.

In practice, when it is 9:00 AM in IRST it is 6:30 AM in Dublin. Midnight in IRST is 9:30 PM in Dublin.Dublin observes daylight saving time while IRST does not, so the gap narrows or widens by an hour part of the year.

IRST to Dublin time conversion table

IRST (IRST)	Dublin (IST)	Day
12:00 AM	9:30 PM	previous day
6:00 AM	3:30 AM	same day
7:00 AM	4:30 AM	same day
8:00 AM	5:30 AM	same day
9:00 AM	6:30 AM	same day
12:00 PM	9:30 AM	same day
3:00 PM	12:30 PM	same day
5:00 PM	2:30 PM	same day
6:00 PM	3:30 PM	same day
9:00 PM	6:30 PM	same day

Why people convert IRST to Dublin time

Scheduling a call from IRST to Dublin: a 10:00 AM start in IRST lands at 7:30 AM in Dublin, so you can confirm the slot without doing the arithmetic yourself.
Finding shared working hours: both IRST and Dublin are inside the 9-to-5 working day between 11:30 AM and 5:00 PM IRST time (9:00 AM–2:30 PM IST). That is roughly 5 hours 30 minutes of usable overlap.
Coordinating a IRST-based team with Dublin 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 -2h 30m gap is not.
Block 11:30 AM–5:00 PM IRST as the recurring meeting window if you work primarily from IRST and need Dublin colleagues present.
Dublin: Clocks fall back on Sun, Oct 25, 2026. Any meeting series spanning that date will shift by an hour in local 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.

About GMT (Greenwich Mean Time)

Greenwich Mean Time (GMT) is the clock time at the Royal Observatory in Greenwich, London, which sits on the Prime Meridian (0° longitude). GMT serves as the reference point from which all other time zones are calculated. The United Kingdom uses GMT during winter months and switches to British Summer Time (BST, UTC+01:00) from late March to late October. Several West African nations use GMT year-round. GMT is often used interchangeably with UTC (Coordinated Universal Time), although technically they are different – UTC is based on atomic clocks while GMT is based on Earth's rotation.

Best time to call between IRST and Dublin

Both IRST and Dublin sit inside the 9 AM – 5 PM working day between 11:30 AM–5:00 PM IRST, which is 9:00 AM–2:30 PM IST. That gives roughly 5 hours and 30 minutes of shared time — the safest window for a live call or meeting.

Business hours overlap

IRST and Dublin share 5 hours of working-hours overlap (11:30 AM–5:00 PM IRST), so scheduling a live meeting is straightforward.

IRST is 2 hours 30 minutes behind Dublin (IRST UTC+03:30 → IST UTC+01:00). The shared working window is 11:30 AM–5:00 PM IRST. Remember to re-check around daylight-saving transitions.

🕐 Daylight Saving Time Info

IRST

Does not observe DST

Dublin

☀ Currently in DST

Standard: UTC+00:00 · DST: UTC+01:00

Clocks fall back on Sun, Oct 25, 2026

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 Dublin?

IRST (IRST, UTC+03:30) is 2 hours 30 minutes behind Dublin (IST, UTC+01:00). The gap is currently -2h 30m.

How do I convert IRST time to Dublin time?

Add -2h 30m to IRST local time. For example, 9:00 AM in IRST is 6:30 AM in Dublin.

What time is it in Dublin right now?

Dublin uses IST at UTC+01:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -2h 30m offset from IRST.

What is the best time to call Dublin from IRST?

Call between 11:30 AM and 5:00 PM IRST — that maps to 9:00 AM–2:30 PM IST and keeps both parties inside the working day.

Which is behind, IRST or Dublin?

IRST is 2 hours 30 minutes behind Dublin. When it is 12:00 PM in IRST it is 9:30 AM in Dublin.

Do IRST and Dublin use different time zones?

IRST uses IRST at UTC+03:30, while Dublin (Ireland) uses IST at UTC+01:00. The IANA identifiers are Asia/Tehran and Europe/Dublin.

Does daylight saving time affect the IRST–Dublin difference?

Yes at the moment: Dublin is on daylight saving time and IRST is not, so the -2h 30m gap shifts by an hour when exactly one of them changes clocks.

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 Dublin?

Not normally. The -2h 30m gap only pushes the date over the previous day.

What is the time difference between IRST and Dublin?

Dublin is -2h 30m from IRST.

What timezone is IRST in?

IRST operates on its local timezone.

What timezone is Dublin in?

Dublin operates on its local timezone.

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 GMT timezone?

Major cities in the GMT timezone include London, Dublin, Lisbon, Accra, Reykjavik, Edinburgh, Casablanca, Dakar.

What is the UTC offset for GMT?

Greenwich Mean Time (GMT) is at UTC+00:00. During daylight saving time, it shifts to BST.

What should I know about the GMT timezone?

GMT is based on the Prime Meridian (0° longitude) passing through Greenwich, London. The Royal Observatory in Greenwich has been the reference point for GMT since 1884.