Convert Greenwich Mean Time to Atlantic Standard Time
Instantly convert Greenwich Mean Time (GMT) to Atlantic Standard Time (AST) with our free online calculator.
Greenwich Mean Time
05:20:58 AM
Wed, Jun 24 (GMT)
Atlantic Standard Time
01:20:58 AM
Wed, Jun 24 (AST)
Convert a Specific Time
24-Hour Comparison
| GMT | AST |
|---|---|
| 12:00 AM | 8:00 PM(-1d) |
| 1:00 AM | 9:00 PM(-1d) |
| 2:00 AM | 10:00 PM(-1d) |
| 3:00 AM | 11:00 PM(-1d) |
| 4:00 AM | 12:00 AM |
| 5:00 AM | 1:00 AM |
| 6:00 AM | 2:00 AM |
| 7:00 AM | 3:00 AM |
| 8:00 AM | 4:00 AM |
| 9:00 AM | 5:00 AM |
| 10:00 AM | 6:00 AM |
| 11:00 AM | 7:00 AM |
| 12:00 PM | 8:00 AM |
| 1:00 PM | 9:00 AM |
| 2:00 PM | 10:00 AM |
| 3:00 PM | 11:00 AM |
| 4:00 PM | 12:00 PM |
| 5:00 PM | 1:00 PM |
| 6:00 PM | 2:00 PM |
| 7:00 PM | 3:00 PM |
| 8:00 PM | 4:00 PM |
| 9:00 PM | 5:00 PM |
| 10:00 PM | 6:00 PM |
| 11:00 PM | 7:00 PM |
How to Convert Greenwich Mean Time to Atlantic Standard Time
Formula
To convert Greenwich Mean Time (GMT) to Atlantic Standard Time (AST): Convert GMT to AST
About Greenwich Mean Time (GMT)
Greenwich Mean Time (GMT, IANA: Europe/London) is the historic and current civil time of the United Kingdom (during winter), Ireland (during winter), Portugal mainland (during winter), Iceland (year-round), and most West African countries. GMT is set at UTC+0 — the time on the Prime Meridian (0° longitude) running through the Royal Observatory in Greenwich, southeast London. Established as the global time reference by the 1884 International Meridian Conference in Washington DC, GMT served as the world's primary civil-time reference from 1884 until 1972 when UTC (Coordinated Universal Time) was adopted as the new precision standard. The UK switches from GMT to British Summer Time (BST = UTC+1) at 01:00 GMT on the last Sunday of March and back to GMT at 02:00 BST on the last Sunday of October per EU Directive 2000/84/EC (UK retained this schedule after Brexit). GMT affects: London Stock Exchange (LSE) trading hours, BBC World Service broadcast time-stamps, all aviation NOTAMs and weather METARs which use UTC = GMT, and ICAO + IMO worldwide maritime/aviation coordination.
About Atlantic Standard Time (AST)
Atlantic Standard Time (AST, IANA: America/Halifax, America/Puerto_Rico) is the time zone for the Canadian Maritime provinces and most of the Caribbean, set at UTC-4:00. AST is observed in: Nova Scotia, New Brunswick, Prince Edward Island, Labrador (partially), Newfoundland's Labrador portion, eastern Quebec, Puerto Rico, US Virgin Islands, Bermuda, Anguilla, Antigua, Aruba, Barbados, British Virgin Islands, Curaçao, Dominica, Grenada, Guadeloupe, Martinique, Saint Lucia, Saint Vincent, Trinidad and Tobago, and Venezuela (since 2007). Canadian Maritime provinces observe AST in winter and switch to ADT = UTC-3:00 in summer per the Energy Policy Act-aligned Canadian schedule. The Caribbean territories (Puerto Rico, USVI, Bermuda) and US territories observe AST year-round without DST per their territorial governments. AST is the same offset as EDT (Eastern Daylight Time) during US summer months, so Halifax and New York are on the same clock in summer but Halifax is one hour ahead in winter.