Convert NPT to AST
AST is 9 hours 45 minutes behind NPT. NPT is UTC+5:45 and AST is UTC−4.
Right now: NPT · AST
Which AST is this?
AST names more than one zone. This page reads it as Atlantic Standard Time at UTC−4, which is the reading most converters take. There is one other: Arabia Standard Time at UTC+3, used in Saudi Arabia, Iraq, Kuwait, Bahrain, Qatar and Yemen.
The letters on a meeting invitation do not say which one is meant. If yours is not Atlantic Standard Time, the answer above is wrong, and not by a little:
| If AST means | Then |
|---|---|
| Atlantic Standard Time — assumed on this page | AST is 9.8 hours behind NPT |
| Arabia Standard Time | AST is 2.8 hours behind NPT |
The large converter sites disagree about this as well: search for a AST conversion and some of the results answer for one reading and some for another, none of them saying which they chose. Where it matters, ask which country the sender is in rather than which letters they typed.
Best time to schedule a meeting
Standard 9–5 working hours do not overlap at all between NPT and AST. Someone has to take an early or late call — or use asynchronous communication instead.
| NPT | AST | Suitable? |
|---|---|---|
| 9:00 AM | 11:15 PM (previous day) | outside 9–5 |
| 10:00 AM | 12:15 AM | outside 9–5 |
| 11:00 AM | 1:15 AM | outside 9–5 |
| 12:00 PM | 2:15 AM | outside 9–5 |
| 1:00 PM | 3:15 AM | outside 9–5 |
| 2:00 PM | 4:15 AM | outside 9–5 |
| 3:00 PM | 5:15 AM | outside 9–5 |
| 4:00 PM | 6:15 AM | outside 9–5 |
| 5:00 PM | 7:15 AM | outside 9–5 |
NPT to AST conversion table
| NPT | AST |
|---|---|
| 12:00 AM | 2:15 PM (previous day) |
| 1:00 AM | 3:15 PM (previous day) |
| 2:00 AM | 4:15 PM (previous day) |
| 3:00 AM | 5:15 PM (previous day) |
| 4:00 AM | 6:15 PM (previous day) |
| 5:00 AM | 7:15 PM (previous day) |
| 6:00 AM | 8:15 PM (previous day) |
| 7:00 AM | 9:15 PM (previous day) |
| 8:00 AM | 10:15 PM (previous day) |
| 9:00 AM | 11:15 PM (previous day) |
| 10:00 AM | 12:15 AM |
| 11:00 AM | 1:15 AM |
| 12:00 PM | 2:15 AM |
| 1:00 PM | 3:15 AM |
| 2:00 PM | 4:15 AM |
| 3:00 PM | 5:15 AM |
| 4:00 PM | 6:15 AM |
| 5:00 PM | 7:15 AM |
| 6:00 PM | 8:15 AM |
| 7:00 PM | 9:15 AM |
| 8:00 PM | 10:15 AM |
| 9:00 PM | 11:15 AM |
| 10:00 PM | 12:15 PM |
| 11:00 PM | 1:15 PM |
About NPT
Nepal Time (NPT) is UTC+5:45. It is used in Nepal, all year.
Nepal Time is UTC+5:45 — the only zone in the world offset by three quarters of an hour, set so that noon falls over Kathmandu rather than over the Indian meridian fifteen minutes away. It breaks almost every piece of software that stores offsets in whole or half hours, and it is fifteen minutes ahead of India rather than the round number people assume.
About AST
Atlantic Standard Time (AST) is UTC−4. It is used in Halifax, Puerto Rico and the eastern Caribbean in winter.
Atlantic Standard Time is UTC−4, one hour ahead of Eastern. It covers Canada's Atlantic provinces, Puerto Rico and much of the eastern Caribbean, and it is the reason a call from Halifax to Toronto is an hour out from what either party expects. The abbreviation is also used for Arabia Standard Time at UTC+3, seven hours away in the other direction, which is a genuinely dangerous collision in scheduling.
Does this gap change with the seasons?
Neither NPT nor AST shifts with the seasons, so this 9.75-hour difference holds all year. That is unusual enough to be worth relying on: most cross-continental gaps move twice a year.
This is the reason scheduling systems store an IANA zone such as Region/City rather than an offset or an abbreviation: the zone knows its own rules and the offset does not.
Frequently asked questions
What time is 9:00 AM NPT in AST?
9:00 AM NPT is 11:15 PM AST (previous day).
Is AST ahead of NPT?
AST is 9 hours 45 minutes behind NPT.
Which time zone does this use?
NPT is UTC+5:45 and AST is UTC−4. Both abbreviations denote a single fixed offset, so this conversion never shifts with daylight saving — what changes is which abbreviation a place is using at the time.