Tehran to London Time
IRST to GMT Converter — 9 AM IRST is 5:30 AM GMT
Tehran is 3 hours and 30 minutes ahead of London. Convert any time between Tehran (IRST/IRDT) and London (GMT/BST) instantly.
Tehran
Iran
London
United Kingdom
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Time Zone Comparison
Tehran to London Time Conversion Table
| Tehran (IRST) | London (GMT) |
|---|---|
| 12:00 AM | 9:30 PM |
| 2:00 AM | 11:30 PM |
| 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 |
Tehran & London — Business & Scheduling Guide
Tehran (Iran) is an important regional economy, with key industries in diverse sectors including services and trade. London (United Kingdom) is a leading center for finance and international trade, known for finance, insurance, media, and professional services. 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 Tehran and London
The 3.5-hour difference between Tehran and London requires careful scheduling. The best overlap window is typically 2–4 hours when both cities are within working hours. Business hours typically follow a 9 AM–5 PM schedule. British business culture values politeness and punctuality, with typical hours of 9 AM–5:30 PM. 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 Tehran and London observe Daylight Saving Time. Tehran uses IRST/IRDT (switching between standard and daylight time), while London uses GMT/BST. 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.
IRST to GMT — Quick Reference
IRST (IRST/IRDT) stands for the timezone used in Tehran, Iran (UTC+3:30). GMT (GMT/BST) is the timezone used in London, United Kingdom (UTC+0). Tehran is 3 hours and 30 minutes ahead of London.
To convert IRST to GMT, subtract 3.5 hours from IRST time. For example, IRST 9:00 AM = GMT 5:30 AM.
Key Facts
- •Time difference: Tehran (UTC+3:30) is 3 hours and 30 minutes ahead of London (UTC+0).
- •Daylight Saving Time: Tehran observes DST (IRST/IRDT). London observes DST (GMT/BST).
- •Regions: Tehran is located in Iran and uses the IRST/IRDT time zone. London is located in United Kingdom and uses the GMT/BST time zone.
- •Best time to call: The best time to call between Tehran and London is 1:00 PM to 4:00 PM in Tehran time, when both cities have overlapping standard working hours.
Frequently Asked Questions
What is the time difference between Tehran and London?
Tehran is 3 hours and 30 minutes ahead of London.
What time is it in London when it's 9 AM in Tehran?
When it's 9:00 AM in Tehran, it is 5:30 AM in London.
What time is 9 PM IRST in GMT?
9 PM IRST (Tehran time) is 5:30 PM GMT (London 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 Tehran and London?
The best time to schedule a meeting is between 1:00 PM to 4:00 PM in Tehran 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 IRST to GMT?
IRST (IRST/IRDT) is the timezone for Tehran, Iran (UTC+3:30). GMT (GMT/BST) is the timezone for London, United Kingdom (UTC+0). Tehran is 3 hours and 30 minutes ahead of London. Quick examples: 9 AM IRST = 5:30 AM GMT, 12 PM IRST = 8:30 AM GMT, 3 PM IRST = 11:30 AM GMT, 6 PM IRST = 2:30 PM GMT.
Is Tehran ahead of or behind London?
Tehran is 3 hours 30 minutes ahead of London. When it's noon in Tehran, it's 8:30 AM in London.
Does Tehran or London change clocks for Daylight Saving Time?
Yes, Tehran observes DST and switches between IRST/IRDT. London observes DST and switches between GMT/BST.
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