AST to UTC Converter & Meeting Planner
Quick answer: 9:00 AM AST = 1:00 PM UTC (fixed -04:00 standard offset — not DST-adjusted). Use the interactive converter below for DST-aware local-time scheduling.
Planning a call or meeting between Atlantic Standard Time (AST) and Coordinated Universal Time (UTC)? You need to account for the standard time difference. Coordinated Universal Time is normally 4 hours ahead of Atlantic Standard Time. Whether you are coordinating between teams in Halifax and San Juan and Greenwich / London, our live tool has you covered. Use our interactive overlap studio below to find the perfect waking hours for both regions, taking into account any seasonal Daylight Saving Time (DST) changes.
24-Hour Conversion Table
Quick reference: 12:00 AM AST = 4:00 AM UTC. The full 24-hour AST to UTC table below uses fixed standard offsets for exact abbreviation searches.
Example: 3:00 PM AST = 7:00 PM UTC.
| AST Time | UTC Time |
|---|---|
| 12:00 AM (00:00) | 4:00 AM (04:00) |
| 1:00 AM (01:00) | 5:00 AM (05:00) |
| 2:00 AM (02:00) | 6:00 AM (06:00) |
| 3:00 AM (03:00) | 7:00 AM (07:00) |
| 4:00 AM (04:00) | 8:00 AM (08:00) |
| 5:00 AM (05:00) | 9:00 AM (09:00) |
| 6:00 AM (06:00) | 10:00 AM (10:00) |
| 7:00 AM (07:00) | 11:00 AM (11:00) |
| 8:00 AM (08:00) | 12:00 PM (12:00) |
| 9:00 AM (09:00) | 1:00 PM (13:00) |
| 10:00 AM (10:00) | 2:00 PM (14:00) |
| 11:00 AM (11:00) | 3:00 PM (15:00) |
| 12:00 PM (12:00) | 4:00 PM (16:00) |
| 1:00 PM (13:00) | 5:00 PM (17:00) |
| 2:00 PM (14:00) | 6:00 PM (18:00) |
| 3:00 PM (15:00) | 7:00 PM (19:00) |
| 4:00 PM (16:00) | 8:00 PM (20:00) |
| 5:00 PM (17:00) | 9:00 PM (21:00) |
| 6:00 PM (18:00) | 10:00 PM (22:00) |
| 7:00 PM (19:00) | 11:00 PM (23:00) |
| 8:00 PM (20:00) | 12:00 AM (00:00)+1 day |
| 9:00 PM (21:00) | 1:00 AM (01:00)+1 day |
| 10:00 PM (22:00) | 2:00 AM (02:00)+1 day |
| 11:00 PM (23:00) | 3:00 AM (03:00)+1 day |
Best time to call Greenwich / London from Halifax
For most work calls, compare the normal business day in Halifax (AST) with the business day in Greenwich / London (UTC). AST commonly covers North America, Caribbean, while UTC is mainly associated with Global.
⚠️ Note: 2026-07-05 is not a normal workday in one or both regions based on their configured calendar. The overlap below should be treated as a reference, not a guaranteed office-hours window.
✅ The most practical overlap on 2026-07-05 is usually 9:00 AM - 2:00 PM AST, which corresponds to 12:00 PM - 5:00 PM UTC. This window sits inside the typical AST workday (9:00 AM - 5:00 PM) and the UTC workday (9:00 AM - 5:00 PM).
- DST Safety: AST or UTC may shift during Daylight Saving Time. Always confirm the converted time for your specific date.
🔥 Popular AST & UTC Converters
Frequently searched time zone conversions related to your search.
Related Time Converters
Explore nearby time zone offsets and reverse conversions related to AST and UTC.
Frequently Asked Questions
What is the time difference between AST and UTC?
During standard time, Coordinated Universal Time is 4 hours ahead of Atlantic Standard Time.
Does the Caribbean observe Daylight Saving Time?
The vast majority of Caribbean nations and territories — including Puerto Rico, the Dominican Republic, the US Virgin Islands, Trinidad and Tobago, and Barbados — do not observe Daylight Saving Time and remain on AST (UTC-4) year-round. This means these territories share the same clock as Halifax only during the Atlantic Standard Time window in winter, diverging by one hour once Canada and Bermuda advance to ADT each spring.
What is the difference between AST and ADT?
AST (Atlantic Standard Time) is the standard winter offset at UTC-4:00, observed from the first Sunday in November through the second Sunday in March across all AST regions. ADT (Atlantic Daylight Time) is the summer offset at UTC-3:00, applied by Eastern Canadian provinces and Bermuda when they advance their clocks by one hour during Daylight Saving Time.