Tehran to Colombo
+2hTehran
IRSTSOURCEColombo
ISTGreen 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 (India Standard Time) timezone regions across the globe.
IRST – Iran Standard Time
UTC+03:30Iran Standard Time (IRST) is the time zone for Iran, 3 hours and 30 minutes ahead of UTC.
- •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.
IST – India Standard Time
UTC+05:30India Standard Time (IST) is the time zone for India and Sri Lanka, 5 hours and 30 minutes ahead of UTC.
- •India is 10 hours 30 minutes ahead of EST and 5 hours 30 minutes ahead of GMT.
- •India uses a single time zone despite spanning 30° of longitude.
- •IST is one of only a handful of time zones with a 30-minute offset.
- •IST is the most populous single time zone in the world with over 1.4 billion people.
- •The Bombay Stock Exchange (BSE) and National Stock Exchange (NSE) operate on IST.
About Tehran
WikipediaTehran operates on Iran Standard Time (IRST), UTC+3:30. Iran's unique half-hour offset makes Tehran time distinctive for regional business coordination.
Iran Standard Time (IRST) is one of few timezones with a 30-minute offset (UTC+3:30).
About Colombo
WikipediaColombo operates on Sri Lanka Time (SLST), UTC+5:30. Sharing India's timezone, Colombo is a key South Asian trade and tourism hub.
Sri Lanka Standard Time (SLST) uses UTC+5:30, same offset as India.
Comparing Time Zones: Tehran and Colombo
Tehran runs on Iran Standard Time (IRST) at UTC+03:30. Colombo runs on India Standard Time (IST) at UTC+05:30. That puts Tehran 2 hours ahead of Colombo — a difference of +2h at the current offsets.
In practice, when it is 9:00 AM in Tehran it is 11:00 AM in Colombo. Midnight in Tehran is 2:00 AM in Colombo. Neither zone observes daylight saving time, so the offset between them stays constant all year.
Tehran to Colombo time conversion table
| Tehran (IRST) | Colombo (IST) | Day |
|---|---|---|
| 12:00 AM | 2:00 AM | same day |
| 6:00 AM | 8:00 AM | same day |
| 7:00 AM | 9:00 AM | same day |
| 8:00 AM | 10:00 AM | same day |
| 9:00 AM | 11:00 AM | same day |
| 12:00 PM | 2:00 PM | same day |
| 3:00 PM | 5:00 PM | same day |
| 5:00 PM | 7:00 PM | same day |
| 6:00 PM | 8:00 PM | same day |
| 9:00 PM | 11:00 PM | same day |
Why people convert Tehran to Colombo time
- Scheduling a call from Tehran to Colombo: a 10:00 AM start in Tehran lands at 12:00 PM in Colombo, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both Tehran and Colombo are inside the 9-to-5 working day between 9:00 AM and 3:00 PM IRST time (11:00 AM–5:00 PM IST). That is roughly 6 hours of usable overlap.
- Booking travel or deliveries: tracking Colombo local time against Tehran keeps pickup windows and arrival estimates honest across the +2h offset.
- Always state the zone abbreviation, not just the hour. "3:00 PM IRST" is unambiguous; "3 PM" across a +2h gap is not.
- Block 9:00 AM–3:00 PM IRST as the recurring meeting window if you work primarily from Tehran and need Colombo colleagues present.
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 IST (India Standard Time)
India Standard Time (IST) is the time observed throughout India and Sri Lanka. It is based on the 82.5°E meridian, passing through Mirzapur in Uttar Pradesh. India uses a single time zone despite spanning roughly 30° of longitude, which has been debated. IST does not observe daylight saving time. India is the world's most populous country, making IST one of the most-used time zones globally. The IT outsourcing industry and call centers operate primarily on IST, making the EST-to-IST conversion one of the most searched timezone conversions.
Best time to call between Tehran and Colombo
Both Tehran and Colombo sit inside the 9 AM – 5 PM working day between 9:00 AM–3:00 PM IRST, which is 11:00 AM–5:00 PM IST. That gives roughly 6 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
Tehran and Colombo share 6 hours of working-hours overlap (9:00 AM–3:00 PM IRST), so scheduling a live meeting is straightforward.
Tehran is 2 hours ahead of Colombo (IRST UTC+03:30 → IST UTC+05:30). The shared working window is 9:00 AM–3:00 PM IRST. Remember to re-check around daylight-saving transitions.
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between Tehran and Colombo?
Tehran (IRST, UTC+03:30) is 2 hours ahead of Colombo (IST, UTC+05:30). The gap is currently +2h.
How do I convert Tehran time to Colombo time?
Add +2h to Tehran local time. For example, 9:00 AM in Tehran is 11:00 AM in Colombo.
What time is it in Colombo right now?
Colombo uses IST at UTC+05:30. Use the live converter at the top of this page — it updates in real time and already accounts for the +2h offset from Tehran.
What is the best time to call Colombo from Tehran?
Call between 9:00 AM and 3:00 PM IRST — that maps to 11:00 AM–5:00 PM IST and keeps both parties inside the working day.
Which is ahead, Tehran or Colombo?
Tehran is 2 hours ahead of Colombo. When it is 12:00 PM in Tehran it is 2:00 PM in Colombo.
Do Tehran and Colombo use different time zones?
Tehran (Iran) uses IRST at UTC+03:30, while Colombo (Sri Lanka) uses IST at UTC+05:30. The IANA identifiers are Asia/Tehran and Asia/Colombo.
Does daylight saving time affect the Tehran–Colombo difference?
Neither zone observes daylight saving time, so the +2h offset between Tehran and Colombo is fixed all year.
Which other cities share Tehran's time zone?
IRST also covers Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.
Which countries use IRST, Tehran's zone?
IRST is used in Iran.
Is there a day difference between Tehran and Colombo?
Not normally. The +2h gap only pushes the date over for late-evening times.
What is the time difference between Tehran and Colombo?
Colombo is +2h from Tehran.
What timezone is Tehran in?
Tehran operates on Iran Standard Time (IRST), UTC+3:30. Iran's unique half-hour offset makes Tehran time distinctive for regional business coordination.
What timezone is Colombo in?
Colombo operates on Sri Lanka Time (SLST), UTC+5:30. Sharing India's timezone, Colombo is a key South Asian trade and tourism hub.
What are the business hours in Tehran?
Standard business hours in Tehran are 8:00 AM - 4:00 PM IRST.
What are the business hours in Colombo?
Standard business hours in Colombo are 9:00 AM - 5:00 PM IST.
What is the best time to schedule a call between Tehran and Colombo?
The best overlap for a call is when both cities are in business hours. Tehran works 8:00 AM - 4:00 PM IRST and Colombo works 9:00 AM - 5:00 PM IST (+2h difference). Try scheduling during the overlapping window for maximum convenience.
What currencies are used in Tehran and Colombo?
Tehran uses IRR (﷼) while Colombo uses LKR (Rs). Check current exchange rates when planning travel or business between these cities.
How do Tehran and Colombo compare in size?
Tehran has a population of approximately 9.4 million (metro: 16.8 million), while Colombo has approximately 752,000 (metro: 5.6 million).
What are the major landmarks in Tehran and Colombo?
Tehran is known for Azadi Tower, Golestan Palace, Grand Bazaar. Colombo is famous for Galle Face Green, Gangaramaya Temple, Colombo Lotus Tower.
Do Tehran and Colombo have stock exchanges?
Yes. Tehran has the TSE (Tehran Stock Exchange) and Colombo has the CSE (Colombo Stock Exchange). The +2h time difference affects trading hour overlaps between these exchanges.
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 IST timezone?
Major cities in the IST timezone include Mumbai, Delhi, Bangalore, Kolkata, Chennai, Hyderabad, Pune, Ahmedabad.
What is the UTC offset for IST?
India Standard Time (IST) is at UTC+05:30.
What should I know about the IST timezone?
India is 10 hours 30 minutes ahead of EST and 5 hours 30 minutes ahead of GMT. India uses a single time zone despite spanning 30° of longitude.
When is it midnight in Tehran, what time is it in Colombo?
When it is 12:00 AM (midnight) in Tehran (IRST), it is +2h later in Colombo (IST).
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