Convert MST to EST
To convert MST to EST: 9:00 AM MST is 11:00 AM EST. MST is UTC-07:00 and EST is UTC-05:00, so EST is 2 hours ahead of MST, all year.
In Eastern Standard Time
- On a 24-hour clock
- 09:00 MST is 11:00 EST
- The offsets
- MST is UTC-07:00, EST is UTC-05:00
- Difference
- EST is 2 hours ahead of MST
- Date
- Same calendar day.
- This gap holds all year
- Both zones switch on the same dates, so they move together.
- MST is only in force part of the year United States: daylight time starts the second Sunday in March, at 02:00 local time and ends the first Sunday in November, at 02:00 local time (Energy Policy Act of 2005, in force since 2007). In 2026 that is 2026-03-08 to 2026-11-01. Denver is on MDT between those dates.
- otherwise MDT, UTC-06:00
- Military time zone letters Z (Zulu) is UTC. A to M run east of Greenwich an hour apart, N to Y west, and J is left out. A letter names an offset, so a zone that switches to daylight time changes letter: EST is R, EDT is Q.
- MST is T (Tango), EST is R (Romeo)
- In every zone
- HST 06:00 AKST 07:00 PST 08:00 AKDT 08:00 MST 09:00 PDT 09:00 CST 10:00 MDT 10:00 EST 11:00 CDT 11:00 EDT 12:00 UTC 16:00 GMT 16:00 BST 17:00 CET 17:00 CEST 18:00 EET 18:00 EEST 19:00 MSK 19:00 IST 21:30 SGT 00:00 HKT 00:00 JST 01:00 AEST 02:00 AEDT 03:00 NZST 04:00 NZDT 05:00
How the Time Zone Converter works
Mountain Standard Time (MST) is UTC-07:00 and Eastern Standard Time (EST) is UTC-05:00, so converting MST to EST means adding 2 hours to the MST time. EST is 2 hours ahead of MST.
Worked through: 9:00 AM MST is 11:00 AM EST.
The gap between these two does not change during the year. Both switch to daylight saving on the same dates under the United States rule (the second Sunday in March, at 02:00 local time, ending the first Sunday in November, at 02:00 local time), so they move together and the difference between them never does. The daylight-time pairing is the same 2 hours.
Two hours forward, with one large exception that makes this the least reliable pair in North America. Most of Arizona never leaves MST, so for the eight months the rest of the country is on daylight time, Phoenix is effectively on Pacific time and is three hours behind New York rather than two. Denver and Phoenix share a standard zone and spend most of the year an hour apart. If the Mountain end of this conversion is in Arizona, the answer here is right for four months and wrong for eight.
One thing worth stating plainly, because it is the most common mistake in this whole subject: an abbreviation is not a place. MST is Mountain Standard Time, which Denver uses only part of the year; the rest of the time it is on MDT at UTC-06:00. EST is likewise only in force for part of the year in New York; otherwise it is EDT at UTC-04:00. If what you have is a city and a date rather than a pair of abbreviations, that is a different question and needs the tz database, not arithmetic. This is also why the shifting designations exist: MT means Mountain time whichever of the two is in force, and ET means Eastern time whichever of the two is in force. Searching for MT to ET and searching for MST to EST are the same question in two vocabularies, which is why this converter answers both.
Common times for this pair:
- 8:00 AM MST is 10:00 AM EST - 9:00 AM MST is 11:00 AM EST - 2:00 PM MST is 4:00 PM EST - 5:00 PM MST is 7:00 PM EST
Time Zone Converter FAQ
What is the time difference between MST and EST?
EST is 2 hours ahead of MST. MST is UTC-07:00 and EST is UTC-05:00, and both offsets are definitions rather than measurements, so the subtraction is exact.
What time is 9:00 AM MST in EST?
9:00 AM MST is 11:00 AM EST. Add 2 hours and carry the date if it crosses midnight.
Does the difference between MST and EST change with daylight saving?
No. Both switch on the same dates, so they move together and the gap between them stays at 2 hours.
Is there anything specific to this pair worth knowing?
Two hours forward, with one large exception that makes this the least reliable pair in North America. Most of Arizona never leaves MST, so for the eight months the rest of the country is on daylight time, Phoenix is effectively on Pacific time and is three hours behind New York rather than two. Denver and Phoenix share a standard zone and spend most of the year an hour apart. If the Mountain end of this conversion is in Arizona, the answer here is right for four months and wrong for eight.
Someone wrote MST but it is summer. What do they mean?
Almost certainly the zone rather than the abbreviation: Denver time, which in summer is MDT at UTC-06:00 rather than MST at UTC-07:00. People type the standard-time abbreviation all year round. If an invitation is an hour out from what you calculated, this is why.