GMT to IRT Time Converter

Convert Greenwich Mean Time (GMT) to Iran Standard Time (IRT). Both time zones are shown live below; current offset between them is 2h 30m ahead.

London · Greenwich Mean Time
12:20:42
Tuesday, May 12, 2026
GMT+1 · UTC+01:00
Tehran · Iran Standard Time
14:50:42
Tuesday, May 12, 2026
GMT+3:30 · UTC+03:30

Convert a specific time

From: GMT (London)
To: IRT (Tehran)
--:--

Daylight Saving status right now

GMT (Greenwich Mean Time)
Observes DST
Yes
In DST right now
Yes
Next fall back
2026-10-25
Offset shift
UTC+01:00 → UTC+00:00
IRT (Iran Standard Time)
Observes DST
No

Heads up: GMT observes DST while IRT does not. The 2.5-hour difference shown above will shift by one hour when GMT starts or ends DST.

When can GMT and IRT meet?

00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
GMT
IRT
Both zones in working hours (9am-5pm)
One zone working
Off-hours
Columns are hours of the day in London (GMT). Each row shows the local working-hours state in that zone for the same moment in time.
6 hours of overlap during standard 9am-5pm working hours.
Best meeting window: 09:00–14:00 GMT (11:30–16:30 IRT).

Hour-by-hour GMT to IRT conversion table

GMT time (London)IRT time (Tehran)Status
00:00 Tue02:30 TueOff-hours both sides
01:00 Tue03:30 TueOff-hours both sides
02:00 Tue04:30 TueOff-hours both sides
03:00 Tue05:30 TueOff-hours both sides
04:00 Tue06:30 TueOff-hours both sides
05:00 Tue07:30 TueOff-hours both sides
06:00 Tue08:30 TueOff-hours both sides
07:00 Tue09:30 TueIRT working
08:00 Tue10:30 TueIRT working
09:00 Tue11:30 TueBoth at work
10:00 Tue12:30 TueBoth at work
11:00 Tue13:30 TueBoth at work
12:00 Tue14:30 TueBoth at work
13:00 Tue15:30 TueBoth at work
14:00 Tue16:30 TueBoth at work
15:00 Tue17:30 TueGMT working
16:00 Tue18:30 TueGMT working
17:00 Tue19:30 TueOff-hours both sides
18:00 Tue20:30 TueOff-hours both sides
19:00 Tue21:30 TueOff-hours both sides
20:00 Tue22:30 TueOff-hours both sides
21:00 Tue23:30 TueOff-hours both sides
22:00 Tue00:30 WedOff-hours both sides
23:00 Tue01:30 WedOff-hours both sides

Times computed for today in each zone using the IANA time zone database. The conversion accounts for daylight saving time wherever applicable.

About these time zones

Greenwich Mean Time (GMT)
IANA identifier
Europe/London
Current UTC offset
UTC+01:00
Current abbreviation
GMT+1
Major cities in this zone
LondonManchesterEdinburghBirmingham
Iran Standard Time (IRT)
IANA identifier
Asia/Tehran
Current UTC offset
UTC+03:30
Current abbreviation
GMT+3:30
Major cities in this zone
TehranIsfahan

Sun today in London and Tehran

London
Sunrise
05:14
Sunset
20:41
Solar noon
12:58
Daylight
15h 26m
Tehran
Sunrise
05:03
Sunset
19:00
Solar noon
12:02
Daylight
13h 57m

Related converters

IRT to GMT (reverse)GMT to ESTGMT to PSTGMT to UTCGMT to CETGMT to ISTEST to IRTPST to IRTUTC to IRTCET to IRTIST to IRT
Looking for local time? See time in London or time in Tehran.

Frequently asked questions

What is the time difference between GMT and IRT right now?+
IRT (Iran Standard Time) is currently 2h 30m ahead GMT (Greenwich Mean Time). The exact difference can change when one or both zones transition into or out of daylight saving time.
Does GMT or IRT observe daylight saving time?+
GMT: observes daylight saving time. IRT: does not observe daylight saving time.
When is the best time to schedule a meeting between GMT and IRT?+
The strongest overlap is 09:00–14:00 GMT (11:30–16:30 IRT), giving 6 hours when both sides are within standard 9am-5pm working hours.
What time is it in Tehran when it is 12:00 noon in London?+
When it is 12:00 Tue in London (GMT), it is 14:30 Tue in Tehran (IRT).
Which IANA time zone identifiers are used for GMT and IRT?+
GMT maps to "Europe/London" in the IANA database. IRT maps to "Asia/Tehran". These identifiers are what most software libraries use to convert times accurately, including DST handling.
Is London ahead of or behind Tehran?+
Whether London (GMT) is ahead of or behind Tehran (IRT) depends on the current UTC offsets. Right now IRT is 2h 30m ahead GMT. The live converter and side-by-side clocks above always reflect the current direction.
What are the current UTC offsets for GMT and IRT?+
GMT is UTC+01:00 (GMT+1) and IRT is UTC+03:30 (GMT+3:30). Both offsets shift by one hour when the corresponding region enters or exits daylight saving time, so the live values on this page are the source of truth.
Can I schedule meetings during business hours for both GMT and IRT?+
Yes. There are 6 hours of overlap during standard 9am-5pm working hours, with the strongest window at 09:00–14:00 GMT.