Tehran to Colombo Time
IRST to IST Converter — 9 AM IRST is 11:00 AM IST
Tehran is 2 hours behind Colombo. Convert any time between Tehran (IRST/IRDT) and Colombo (IST) instantly.
Tehran
Iran
Colombo
Sri Lanka
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Time Zone Comparison
Tehran to Colombo Time Conversion Table
| Tehran (IRST) | Colombo (IST) |
|---|---|
| 12:00 AM | 2:00 AM |
| 2:00 AM | 4:00 AM |
| 4:00 AM | 6:00 AM |
| 6:00 AM | 8:00 AM |
| 8:00 AM | 10:00 AM |
| 10:00 AM | 12:00 PM |
| 12:00 PM | 2:00 PM |
| 2:00 PM | 4:00 PM |
| 4:00 PM | 6:00 PM |
| 6:00 PM | 8:00 PM |
| 8:00 PM | 10:00 PM |
| 10:00 PM | 12:00 AM |
Tehran & Colombo — Business & Scheduling Guide
Tehran (Iran) is one of the Middle East's largest economies with a young population, with key industries in oil and gas, petrochemicals, automotive, and agriculture. Colombo (Sri Lanka) is a South Asian island economy with strategic Indian Ocean positioning, known for tourism, tea, apparel, and IT/BPO services. With a 2-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 Colombo
With only a 2-hour gap, Tehran and Colombo have generous overlapping work hours. Morning calls in the later time zone align well with mid-day in the other. Iranian business hours are typically 8 AM–4 PM Saturday–Wednesday, with Thursday as a half-day and Friday off. Sri Lankan business hours are typically 8:30 AM–5 PM, with a growing technology outsourcing sector. Most teams find that late morning to early afternoon offers the widest window for collaboration.
Daylight Saving Time Considerations
Tehran observes Daylight Saving Time (IRST/IRDT), but Colombo does not — it stays on IST year-round. This means the time difference between Tehran and Colombo changes by 1 hour when Tehran switches clocks. During Iran's summer, the gap is 1–3 hours instead of the standard 2 hours. Mark DST transition dates on your calendar to avoid missed meetings.
Collaboration Tools & Workflow
Teams working between Tehran and Colombo enjoy strong real-time collaboration potential. With just a 2-hour time difference, daily standups, pair programming, and spontaneous video calls are all practical. Popular tools for Tehran–Colombo teams include Slack for real-time messaging, Google Meet or Zoom for video calls, and Notion or Linear for project management. The overlapping work window is wide enough that most teams can operate nearly synchronously.
Remote Work Between Tehran & Colombo
Tehran, a key city in Iran, and Colombo, a key city in Sri Lanka, are well-connected for remote work. With a manageable 2-hour time difference, distributed teams can maintain a near-synchronous workflow. Both cities have strong internet infrastructure, coworking spaces, and established remote work cultures. For freelancers and remote workers, this time zone pairing is ideal — you can serve clients in Colombo from Tehran (or vice versa) without disrupting your standard workday.
IRST to IST — Quick Reference
IRST (IRST/IRDT) stands for the timezone used in Tehran, Iran (UTC+3:30). IST (IST) is the timezone used in Colombo, Sri Lanka (UTC+5:30). Tehran is 2 hours behind Colombo.
To convert IRST to IST, add 2 hours to IRST time. For example, IRST 9:00 AM = IST 11:00 AM.
Key Facts
- •Time difference: Tehran (UTC+3:30) is 2 hours behind Colombo (UTC+5:30).
- •Daylight Saving Time: Tehran observes DST (IRST/IRDT). Colombo does not observe DST (IST).
- •Regions: Tehran is located in Iran and uses the IRST/IRDT time zone. Colombo is located in Sri Lanka and uses the IST time zone.
- •Best time to call: The best time to call between Tehran and Colombo is 9:00 AM to 2:00 PM in Tehran time, when both cities have overlapping standard working hours.
Frequently Asked Questions
What is the time difference between Tehran and Colombo?
Tehran is 2 hours behind Colombo.
What time is it in Colombo when it's 9 AM in Tehran?
When it's 9:00 AM in Tehran, it is 11:00 AM in Colombo.
What time is 9 PM IRST in IST?
9 PM IRST (Tehran time) is 11:00 PM IST (Colombo 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 Colombo?
The best time to schedule a meeting is between 9:00 AM to 2:00 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 IST?
IRST (IRST/IRDT) is the timezone for Tehran, Iran (UTC+3:30). IST (IST) is the timezone for Colombo, Sri Lanka (UTC+5:30). Tehran is 2 hours behind Colombo. Quick examples: 9 AM IRST = 11:00 AM IST, 12 PM IRST = 2:00 PM IST, 3 PM IRST = 5:00 PM IST, 6 PM IRST = 8:00 PM IST.
Is Tehran ahead of or behind Colombo?
Tehran is 2 hours behind Colombo. When it's noon in Tehran, it's 2:00 PM in Colombo.
Does Tehran or Colombo change clocks for Daylight Saving Time?
Yes, Tehran observes DST and switches between IRST/IRDT. Colombo does not observe DST — it stays on IST year-round. Because only one city observes DST, the time difference shifts by 1 hour during transition periods (typically March/April and October/November).
What time is noon in Tehran in Colombo time?
When it is 12:00 PM (noon) in Tehran (IRST), it is 2:00 PM in Colombo (IST). This is often a popular time for scheduling lunch-hour calls across the Tehran–Colombo corridor.
What are the overlapping work hours between Tehran and Colombo?
The overlapping work hours between Tehran and Colombo are approximately 9:00 AM to 2:00 PM in Tehran time, when both cities are within the standard 9 AM–5 PM workday. This is the ideal window for meetings, pair programming, and real-time collaboration.
What timezone is Tehran in?
Tehran is in the IRST/IRDT time zone (UTC+3:30). It is located in Iran. Tehran observes Daylight Saving Time, switching between IRST/IRDT.
What timezone is Colombo in?
Colombo is in the IST time zone (UTC+5:30). It is located in Sri Lanka. Colombo does not observe Daylight Saving Time.
How do I schedule a call between Tehran and Colombo?
To schedule a call between Tehran and Colombo, aim for the overlapping window of 9:00 AM to 2:00 PM in Tehran time. Use Google Calendar or Calendly with both time zones visible, share the meeting invite with the IST time clearly noted, and always double-check the time difference — especially during DST transitions. Pro tip: include both local times in the calendar invite title (e.g., "Sync — 10 AM IRST / 12:00 PM IST").
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