America/Puerto_Rico time zone
1:02PMAST
ASTUTC−4+1 h vs New York (you)
No transitions: America/Puerto_Rico stays on AST (UTC−4).
About America/Puerto_Rico
America/Puerto_Rico is the IANA time zone for AST: QC (Lower North Shore) in Puerto Rico, Antigua and Barbuda, Canada, Anguilla, Aruba, Saint Barthelemy, Bonaire, Saint Eustatius and Saba , Curacao, Dominica, Grenada, Guadeloupe, Saint Kitts and Nevis, Saint Lucia, Saint Martin, Montserrat, Sint Maarten, Trinidad and Tobago, Saint Vincent and the Grenadines, British Virgin Islands and U.S. Virgin Islands. It currently keeps Atlantic Standard Time (AST, UTC−4) all year.
The zone serves 20 countries or territories because their clocks have agreed since 1970; tzdata lists them together in zone1970.tab. That says nothing about borders or sovereignty, as the file’s header points out.
Its principal location is Puerto Rico at 18.47° N, 66.11° W.
Abbreviations in use: AST. Offset page: UTC−4.
Rule for future years (POSIX TZ string)
AST4
The standard time is called AST and is UTC−4. POSIX writes the offset with the opposite sign (west of Greenwich is positive), which is why the string says "4". There is no daylight saving rule: the zone stays on this offset for every year after the end of its explicit transitions. Software that has no full tzdata copy, such as many embedded devices, can use this string directly as the TZ environment variable.
History of America/Puerto_Rico since 1970
The record starts with local mean time (UTC−4:24), which ended on March 28, 1899. The first daylight saving time in the record is in 1942.
| Years | Clocks | Abbreviations |
|---|---|---|
| 1970 onward | UTC−4 all year | AST |
Before 1970
3 offset changes before 1970 in the record:
- Tuesday, March 28, 1899: UTC−4:24 → UTC−4 (AST)
- Sunday, May 3, 1942: UTC−4 → UTC−3 (AWT), daylight saving time
- Sunday, September 30, 1945: UTC−3 → UTC−4 (AST)
tzdata commits to accuracy from 1970 for every zone (zone1970.tab); earlier entries are historical research and may be incomplete.
Aliases and zones with the same clock
These older or country-specific IDs are links to America/Puerto_Rico in tzdata. Their pages redirect here: America/Anguilla, America/Antigua, America/Aruba, America/Blanc-Sablon, America/Curacao, America/Dominica, America/Grenada, America/Guadeloupe, America/Kralendijk, America/Lower_Princes, America/Marigot, America/Montserrat, America/Port_of_Spain, America/St_Barthelemy, America/St_Kitts, America/St_Lucia, America/St_Thomas, America/St_Vincent, America/Tortola, America/Virgin.
Other zones that keep exactly the same time under the current rules (but have a different history): America/Barbados, America/Boa_Vista, America/Campo_Grande, America/Caracas, America/Cuiaba, America/Guyana, America/La_Paz, America/Manaus, America/Martinique, America/Porto_Velho, America/Santo_Domingo.
Places on America/Puerto_Rico
Convert Puerto Rico time
Using America/Puerto_Rico in code
Every major platform reads the same IANA ID. Store instants in UTC and convert with the ID at display time; never store a fixed offset for a place that has daylight saving time.
// JavaScript
new Date().toLocaleString('en-US', { timeZone: 'America/Puerto_Rico' })
# Python 3.9+
from zoneinfo import ZoneInfo
from datetime import datetime
datetime.now(ZoneInfo('America/Puerto_Rico'))
// Java
java.time.ZonedDateTime.now(java.time.ZoneId.of("America/Puerto_Rico"))
// Go
loc, _ := time.LoadLocation("America/Puerto_Rico")
time.Now().In(loc)
-- PostgreSQL
SELECT now() AT TIME ZONE 'America/Puerto_Rico';
# Shell
TZ='America/Puerto_Rico' datePlatforms ship their own copy of tzdata and update it on their own schedule. After a rule change, outputs can differ until the platform updates; this page uses tzdata 2026f.