CDT to Colombo
+10h 30mCDT
CDTSOURCEColombo
ISTGreen rows indicate typical business hours (9 AM - 5 PM)
CDT and IST on the World Map
The map below highlights the CDT (Central Daylight Time) and IST (India Standard Time) timezone regions across the globe.
CDT – Central Daylight Time
UTC-05:00Central Daylight Time (CDT) is the daylight saving offset in the Central Time Zone, 5 hours behind UTC.
- •CDT is the same offset as EST (UTC-05:00), which can cause confusion.
- •CDT runs from the second Sunday in March to the first Sunday in November.
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 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.
Understanding the +10h 30m Gap: CDT vs Colombo
CDT runs on Central Daylight Time (CDT) at UTC-05:00. Colombo runs on India Standard Time (IST) at UTC+05:30. That puts CDT 10 hours 30 minutes ahead of Colombo — a difference of +10h 30m at the current offsets.
In practice, when it is 9:00 AM in CDT it is 7:30 PM in Colombo. Midnight in CDT is 10:30 AM in Colombo. Neither zone observes daylight saving time, so the offset between them stays constant all year.
CDT to Colombo time conversion table
| CDT (CDT) | Colombo (IST) | Day |
|---|---|---|
| 12:00 AM | 10:30 AM | same day |
| 6:00 AM | 4:30 PM | same day |
| 7:00 AM | 5:30 PM | same day |
| 8:00 AM | 6:30 PM | same day |
| 9:00 AM | 7:30 PM | same day |
| 12:00 PM | 10:30 PM | same day |
| 3:00 PM | 1:30 AM | next day |
| 5:00 PM | 3:30 AM | next day |
| 6:00 PM | 4:30 AM | next day |
| 9:00 PM | 7:30 AM | next day |
Why people convert CDT to Colombo time
- Scheduling a call from CDT to Colombo: a 10:00 AM start in CDT lands at 8:30 PM in Colombo, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +10h 30m gap: CDT and Colombo have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in Colombo is 7:30 PM in CDT.
- Coordinating a CDT-based team with Colombo contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.
- Always state the zone abbreviation, not just the hour. "3:00 PM CDT" is unambiguous; "3 PM" across a +10h 30m gap is not.
- With a +10h 30m gap there is no shared 9-to-5 window, so alternate the early start: one week CDT takes the early slot, the next week Colombo does.
About CDT (Central Daylight Time)
Central Daylight Time (CDT) is observed during summer months in the US and Canadian portions of the Central Time Zone. Clocks are moved forward by one hour, aligning with Eastern Standard Time (EST). Most of Mexico and Central America do not observe CDT, staying on CST year-round.
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 CDT and Colombo
With a +10h 30m offset there is no overlap inside a normal 9 AM – 5 PM day. Colombo opens at 9:00 AM IST, which is 7:30 PM in CDT, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
CDT and Colombo have no shared working hours because of the +10h 30m gap. Teams need to alternate early starts or rely on asynchronous handovers.
CDT is 10 hours 30 minutes ahead of Colombo (CDT UTC-05:00 → IST UTC+05:30). There is no shared 9-to-5 window, so plan around an early or late slot. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
CDT
☀ Currently in DST
Standard: UTC-06:00 · DST: UTC-05:00
Clocks fall back on Sun, Nov 1, 2026
Colombo
Does not observe DST
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 CDT and Colombo?
CDT (CDT, UTC-05:00) is 10 hours 30 minutes ahead of Colombo (IST, UTC+05:30). The gap is currently +10h 30m.
How do I convert CDT time to Colombo time?
Add +10h 30m to CDT local time. For example, 9:00 AM in CDT is 7:30 PM 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 +10h 30m offset from CDT.
What is the best time to call Colombo from CDT?
There is no shared working-hours window because of the +10h 30m gap. The closest option is 1:00 PM in CDT, which is 11:30 PM in Colombo.
Which is ahead, CDT or Colombo?
CDT is 10 hours 30 minutes ahead of Colombo. When it is 12:00 PM in CDT it is 10:30 PM in Colombo.
Do CDT and Colombo use different time zones?
CDT uses CDT at UTC-05:00, while Colombo (Sri Lanka) uses IST at UTC+05:30. The IANA identifiers are America/Chicago and Asia/Colombo.
Does daylight saving time affect the CDT–Colombo difference?
Neither zone observes daylight saving time, so the +10h 30m offset between CDT and Colombo is fixed all year.
Which other cities share CDT's time zone?
CDT also covers Chicago, Houston, Dallas, Austin, Winnipeg, Nashville.
Which countries use CDT, CDT's zone?
CDT is used in United States (Central), Canada (Manitoba).
Is there a day difference between CDT and Colombo?
Not normally. The +10h 30m gap only pushes the date over for late-evening times.
What is the time difference between CDT and Colombo?
Colombo is +10h 30m from CDT.
What timezone is CDT in?
CDT operates on its local timezone.
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 Colombo?
Standard business hours in Colombo are 9:00 AM - 5:00 PM IST.
Which countries use CDT (Central Daylight Time)?
CDT is used in United States (Central), Canada (Manitoba).
Does CDT observe daylight saving time?
Yes, CDT switches to CST during summer months.
What are some interesting facts about CDT?
CDT is the same offset as EST (UTC-05:00), which can cause confusion. CDT runs from the second Sunday in March to the first Sunday in November.
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 CDT, what time is it in Colombo?
When it is 12:00 AM (midnight) in CDT (CDT), it is +10h 30m later in Colombo (IST).
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