AST to MST Converter
Mountain Time (MST / MDT) is 3 hours behind Atlantic Time (AST / ADT).
Quick Reference
- Atlantic Time
- ADT (GMT-3)
AST starts on Nov 1, 2026
- Mountain Time
- MDT (GMT-6)
MST starts on Nov 1, 2026
Cities in AST
Cities in MST
Frequently Asked Questions
- What is the difference between AST and MST?
- MST is 3 hours behind AST.
- How do I convert AST to MST?
- To convert from AST to MST, subtract 3 hours. Use the interactive converter on this page to convert specific times.
- What cities are in AST and MST?
- Cities in AST include Halifax, Charlottetown. Cities in MST include Denver, El Paso, Albuquerque, Colorado Springs, Salt Lake City.