MST to AST Converter
Convert Mountain Standard Time (MST) to Atlantic Standard Time (AST) in one step. Because aST is 3 hours ahead of MST, the math is a fixed 3 hours shift. Adjust the time or date and watch it update.
Daylight saving notes
In the United States and Canada, daylight saving time runs from the second Sunday in March to the first Sunday in November. That affects Mountain Standard Time (MST).
MST to AST conversion chart
For example, a 9:00 AM MST meeting takes place at 12:00 PM AST. Concretely, when Denver (MST) and Halifax (AST) set up a call, aST is 3 hours ahead of MST.
| MST time | AST time |
|---|---|
| 12:00 AM | 3:00 AM |
| 1:00 AM | 4:00 AM |
| 2:00 AM | 5:00 AM |
| 3:00 AM | 6:00 AM |
| 4:00 AM | 7:00 AM |
| 5:00 AM | 8:00 AM |
| 6:00 AM | 9:00 AM |
| 7:00 AM | 10:00 AM |
| 8:00 AM | 11:00 AM |
| 9:00 AM | 12:00 PM |
| 10:00 AM | 1:00 PM |
| 11:00 AM | 2:00 PM |
| 12:00 PM | 3:00 PM |
| 1:00 PM | 4:00 PM |
| 2:00 PM | 5:00 PM |
| 3:00 PM | 6:00 PM |
| 4:00 PM | 7:00 PM |
| 5:00 PM | 8:00 PM |
| 6:00 PM | 9:00 PM |
| 7:00 PM | 10:00 PM |
| 8:00 PM | 11:00 PM |
| 9:00 PM | 12:00 AM+1 day |
| 10:00 PM | 1:00 AM+1 day |
| 11:00 PM | 2:00 AM+1 day |
This chart uses the fixed MST and AST offsets; the live converter above follows current daylight saving.
Convert MST to AST Time Zone
Below are the answers people search for most when converting Mountain Standard Time (MST) to Atlantic Standard Time (AST).
Converting MST to AST, step by step
It takes three quick steps:
- Click the MST field on the left and pick the time you want to convert.
- The matching AST time updates on the right automatically — there’s no button to press.
- Need a different day? Click the date field and the result follows, rolling over if it crosses midnight.
MST vs AST: what's the time gap?
AST is 3 hours ahead of MST. In everyday terms, once you know the time on one side you just add 3 hours to get the other — so a call between Denver and Halifax is always 3 hours apart.
What's the current time in AST?
Right now the time in Atlantic Standard Time (AST) is Monday, June 29, 2026 · 1:53:56 PM. It ticks every second, so you’re always looking at the live AST clock.
And what time is it in MST?
And in Mountain Standard Time (MST), it’s currently Monday, June 29, 2026 · 10:53:56 AM. Compare the two and the 3 hours gap is easy to see.
What's the best time for a MST–AST call?
For example, a 9:00 AM MST meeting takes place at 12:00 PM AST. The trick is to aim for a slot that lands inside normal working hours on both sides. Once you’ve found a time, hit Share on the converter to copy a link with the time built in — easy to send to a colleague. Juggling three or more zones? The meeting planner highlights the hours that overlap for everyone.
Does daylight saving time change the MST–AST difference?
The labels MST and AST are fixed offsets, so the result on this page is always exact. Both regions move their clocks for daylight saving on roughly the same weekends, so the 3 hours gap usually holds steady right through the year.
How accurate is this MST to AST conversion?
We don’t guess. MST and AST times are worked out from the official IANA time zone database, the trusted standard that operating systems use worldwide. Because daylight-saving rules and regional offsets do change over time, we track those updates rather than relying on a fixed number — which is exactly where many converters slip up.
Convert MST to other time zones
- UTC Coordinated Universal Time
- GMT Greenwich Mean Time
- EST Eastern Standard Time
- EDT Eastern Daylight Time
- CST Central Standard Time
- CDT Central Daylight Time
- MDT Mountain Daylight Time
- PST Pacific Standard Time
- PDT Pacific Daylight Time
- AKST Alaska Standard Time
- AKDT Alaska Daylight Time
- HST Hawaii Standard Time
- AST Atlantic Standard Time
- ADT Atlantic Daylight Time
- NST Newfoundland Standard Time
- NDT Newfoundland Daylight Time
- BRT Brasília Time
- ART Argentina Time
- WET Western European Time
- WEST Western European Summer Time
- CET Central European Time
- CEST Central European Summer Time
- EET Eastern European Time
- EEST Eastern European Summer Time
- BST British Summer Time
- IST Irish Standard Time
- MSK Moscow Standard Time
- TRT Turkey Time
- WAT West Africa Time
- CAT Central Africa Time
- EAT East Africa Time
- SAST South Africa Standard Time
- GST Gulf Standard Time
- IST Israel Standard Time
- IDT Israel Daylight Time
- IST India Standard Time
- PKT Pakistan Standard Time
- BDT Bangladesh Standard Time
- ICT Indochina Time
- WIB Western Indonesian Time
- WITA Central Indonesian Time
- WIT Eastern Indonesian Time
- CST China Standard Time
- HKT Hong Kong Time
- SGT Singapore Time
- PHT Philippine Time
- JST Japan Standard Time
- KST Korea Standard Time
- AWST Australian Western Standard Time
- ACST Australian Central Standard Time
- ACDT Australian Central Daylight Time
- AEST Australian Eastern Standard Time
- AEDT Australian Eastern Daylight Time
- NZST New Zealand Standard Time
- NZDT New Zealand Daylight Time
Convert to AST from other time zones
- UTC Coordinated Universal Time
- GMT Greenwich Mean Time
- EST Eastern Standard Time
- EDT Eastern Daylight Time
- CST Central Standard Time
- CDT Central Daylight Time
- MST Mountain Standard Time
- MDT Mountain Daylight Time
- PST Pacific Standard Time
- PDT Pacific Daylight Time
- AKST Alaska Standard Time
- AKDT Alaska Daylight Time
- HST Hawaii Standard Time
- ADT Atlantic Daylight Time
- NST Newfoundland Standard Time
- NDT Newfoundland Daylight Time
- BRT Brasília Time
- ART Argentina Time
- WET Western European Time
- WEST Western European Summer Time
- CET Central European Time
- CEST Central European Summer Time
- EET Eastern European Time
- EEST Eastern European Summer Time
- BST British Summer Time
- IST Irish Standard Time
- MSK Moscow Standard Time
- TRT Turkey Time
- WAT West Africa Time
- CAT Central Africa Time
- EAT East Africa Time
- SAST South Africa Standard Time
- GST Gulf Standard Time
- IST Israel Standard Time
- IDT Israel Daylight Time
- IST India Standard Time
- PKT Pakistan Standard Time
- BDT Bangladesh Standard Time
- ICT Indochina Time
- WIB Western Indonesian Time
- WITA Central Indonesian Time
- WIT Eastern Indonesian Time
- CST China Standard Time
- HKT Hong Kong Time
- SGT Singapore Time
- PHT Philippine Time
- JST Japan Standard Time
- KST Korea Standard Time
- AWST Australian Western Standard Time
- ACST Australian Central Standard Time
- ACDT Australian Central Daylight Time
- AEST Australian Eastern Standard Time
- AEDT Australian Eastern Daylight Time
- NZST New Zealand Standard Time
- NZDT New Zealand Daylight Time
Frequently asked questions
How many hours ahead of MST is AST?
AST is 3 hours ahead of MST — a fixed 3 hours difference, since both are fixed-offset labels.
What time is it in AST when it's 12:00 PM MST?
When it's 12:00 PM (noon) MST, it's 3:00 PM AST.
Do MST or AST use daylight saving time?
Mountain Standard Time (MST) observes daylight saving, alternating with MDT; Atlantic Standard Time (AST) observes daylight saving, alternating with ADT.
Why might the real-world MST–AST difference change during the year?
The labels MST and AST are fixed offsets, so this converter is always exact. But Mountain Standard Time's region switches between standard and summer time, so for part of the year you may actually want MDT to AST. Always check which label a region is currently using before you schedule.