London to Tehran Time
GMT to IRST Converter — 9 AM GMT is 12:30 PM IRST
London is 3 hours and 30 minutes behind Tehran. Convert any time between London (GMT/BST) and Tehran (IRST/IRDT) instantly.
London
United Kingdom
Tehran
Iran
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Time Zone Comparison
London to Tehran Time Conversion Table
| London (GMT) | Tehran (IRST) |
|---|---|
| 12:00 AM | 2:30 AM |
| 2:00 AM | 4:30 AM |
| 4:00 AM | 6:30 AM |
| 6:00 AM | 8:30 AM |
| 8:00 AM | 10:30 AM |
| 10:00 AM | 12:30 PM |
| 12:00 PM | 2:30 PM |
| 2:00 PM | 4:30 PM |
| 4:00 PM | 6:30 PM |
| 6:00 PM | 8:30 PM |
| 8:00 PM | 10:30 PM |
| 10:00 PM | 12:30 AM |
London & Tehran — Business & Scheduling Guide
London (United Kingdom) is a leading center for finance and international trade, with key industries in finance, insurance, media, and professional services. Tehran (Iran) is an important regional economy, known for diverse sectors including services and trade. With a 3.5-hour time difference, professionals frequently schedule cross-border calls between these two cities for international trade, remote team collaboration, and client meetings.
Scheduling Meetings Between London and Tehran
The 3.5-hour difference between London and Tehran requires careful scheduling. The best overlap window is typically 2–4 hours when both cities are within working hours. British business culture values politeness and punctuality, with typical hours of 9 AM–5:30 PM. Business hours typically follow a 9 AM–5 PM schedule. Teams often designate specific "overlap hours" for real-time collaboration and use asynchronous communication (Slack, email, recorded video) for the rest of the day.
Daylight Saving Time Considerations
Both London and Tehran observe Daylight Saving Time. London uses GMT/BST (switching between standard and daylight time), while Tehran uses IRST/IRDT. If their DST transitions happen on different dates — which is common, as the US, EU, and other regions change clocks on different weekends — the effective time difference between the two cities can shift by 1 hour for several weeks. Always double-check the actual offset during March–April and October–November.
GMT to IRST — Quick Reference
GMT (GMT/BST) stands for the timezone used in London, United Kingdom (UTC+0). IRST (IRST/IRDT) is the timezone used in Tehran, Iran (UTC+3:30). London is 3 hours and 30 minutes behind Tehran.
To convert GMT to IRST, add 3.5 hours to GMT time. For example, GMT 9:00 AM = IRST 12:30 PM.
Key Facts
- •Time difference: London (UTC+0) is 3 hours and 30 minutes behind Tehran (UTC+3:30).
- •Daylight Saving Time: London observes DST (GMT/BST). Tehran observes DST (IRST/IRDT).
- •Regions: London is located in United Kingdom and uses the GMT/BST time zone. Tehran is located in Iran and uses the IRST/IRDT time zone.
- •Best time to call: The best time to call between London and Tehran is 9:00 AM to 1:00 PM in London time, when both cities have overlapping standard working hours.
Frequently Asked Questions
What is the time difference between London and Tehran?
London is 3 hours and 30 minutes behind Tehran.
What time is it in Tehran when it's 9 AM in London?
When it's 9:00 AM in London, it is 12:30 PM in Tehran.
What time is 9 PM GMT in IRST?
9 PM GMT (London time) is 12:30 AM IRST (Tehran time). This is a common time people check when scheduling evening calls across these two time zones.
When is the best time to schedule a meeting between London and Tehran?
The best time to schedule a meeting is between 9:00 AM to 1:00 PM in London time, when both cities are within standard working hours (9 AM – 5 PM). This gives you the maximum overlap window for real-time collaboration.
How do I convert GMT to IRST?
GMT (GMT/BST) is the timezone for London, United Kingdom (UTC+0). IRST (IRST/IRDT) is the timezone for Tehran, Iran (UTC+3:30). London is 3 hours and 30 minutes behind Tehran. Quick examples: 9 AM GMT = 12:30 PM IRST, 12 PM GMT = 3:30 PM IRST, 3 PM GMT = 6:30 PM IRST, 6 PM GMT = 9:30 PM IRST.
Is London ahead of or behind Tehran?
London is 3 hours 30 minutes behind Tehran. When it's noon in London, it's 3:30 PM in Tehran.
Does London or Tehran change clocks for Daylight Saving Time?
Yes, London observes DST and switches between GMT/BST. Tehran observes DST and switches between IRST/IRDT.
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