IANA tz database · zone identifier

America/Santo_Domingo

The IANA tz database identifier for Atlantic Standard Time in Dominican Republic. Store this string — not the abbreviation, not the offset — and your timestamps stay correct forever.

UTC-04:00Abbreviation ASTNo DST — never observed
Time in America/Santo_Domingo☾ Night
19:00:12
Wednesday, July 15, 2026
Offset
UTC-04:00
Abbreviation
AST
DST
No DST

Current offset

UTC-04:00

same year-round

Abbreviation

AST

used year-round

DST behaviour

Never

has never observed daylight saving

Country

🇩🇴 Dominican Republic

ISO 3166: DO · view country page →

Using this identifier

The string to put in your code.

America/Santo_Domingo is the identifier to use in code and config for this region. Every modern language, database, and OS resolves it through the same tz database, so the examples here behave identically everywhere.

Avoid storing AST or -04:00 — abbreviations are ambiguous and fixed offsets can't follow rule changes.

// format a date in this zone
new Intl.DateTimeFormat('en-US', {
timeZone: 'America/Santo_Domingo',
dateStyle: 'full', timeStyle: 'long'
}).format(new Date());

Offset & DST behaviour

One offset,
25 years.

America/Santo_Domingo has kept UTC-04:00 year-round since 3 December 2000 — no daylight saving and no offset changes on record since. It is among the most stable identifiers in the database.

Every offset this zone has kept

−04:39:36UTC-04:00 · UNCHANGED 3 December 2000 NOW

Keeping this offset since

3 December 2000

Next transition

None scheduled

no DST rules exist for this zone

Safe to assume

Local = UTC − 4h, always

…but store the identifier anyway

Technical record

The database entry, in full.

source: IANA tz database

IdentifierAmerica/Santo_Domingo
ISO country codeDO🇩🇴 Dominican Republic
Reference coordinates18.47°N, 69.90°Wtz database reference point
Standard offsetUTC-04:00abbreviation AST
Daylight offset—daylight saving has never been observed

Where it applies

All of Dominican Republic, one clock.

Looking for travel-friendly info? See Santo Domingo or Atlantic Standard Time.

🇩🇴
Dominican Republic

11M people, one time zone. The whole country resolves to America/Santo_Domingo.

Country page →
🇩🇴 Santo Domingo
19:00
19:00:12 · AST
pop. 2.2MAST
🇩🇴 Santo Domingo Oeste
19:00
19:00:12 · AST
pop. 2.2MAST
🇩🇴 Santiago de los Caballeros
19:00
19:00:12 · AST
pop. 1.3MAST

Related identifiers

Nearby in the database.

Same zone group · Atlantic Standard Time

other identifiers keeping AST

America/AnguillaAnguillaAmerica/AntiguaAntigua and BarbudaAmerica/ArubaArubaAmerica/BarbadosBarbadosAmerica/Blanc-SablonCanadaAmerica/CuracaoCuraçaoAmerica/DominicaDominicaAmerica/Glace_BayCanadaAmerica/Goose_BayCanadaAmerica/GrenadaGrenadaAmerica/GuadeloupeGuadeloupeAmerica/HalifaxCanadaAmerica/KralendijkCaribbean NetherlandsAmerica/Lower_PrincesSint MaartenAmerica/MarigotSaint MartinAmerica/MartiniqueMartiniqueAmerica/MonctonCanadaAmerica/MontserratMontserratAmerica/Port_of_SpainTrinidad and TobagoAmerica/Puerto_RicoPuerto RicoAmerica/St_BarthelemySaint BarthélemyAmerica/St_KittsSaint Kitts and NevisAmerica/St_LuciaSaint LuciaAmerica/St_ThomasUnited States Virgin IslandsAmerica/St_VincentSaint Vincent and the GrenadinesAmerica/ThuleGreenlandAmerica/TortolaBritish Virgin IslandsAtlantic/BermudaBermuda

Same offset · UTC-04:00

other zones keeping this offset right now

Frequently asked questions

Answers specific to this identifier — generated from the database record. Can't find what you need? Email [email protected].

What UTC offset is America/Santo_Domingo?
America/Santo_Domingo is UTC-04:00, year-round. The offset never changes because the zone does not observe daylight saving time.
Does America/Santo_Domingo observe daylight saving time?
No. America/Santo_Domingo has never observed DST — it has kept UTC-04:00 continuously since 3 December 2000.
Which country uses America/Santo_Domingo?
Dominican Republic. The identifier covers the whole country.
Is America/Santo_Domingo the same as AST?
America/Santo_Domingo is one of the IANA zones that keeps Atlantic Standard Time (AST). Use America/Santo_Domingo in software — AST is a human-friendly label, not a valid identifier.

Free · Developer API

This zone, as JSON.

Everything on this page — offset, abbreviation, DST rules, coordinates — from one endpoint, always current with the latest tzdb release.

GET /v1/timezones Live

countries, cities, convert, DST transitions coming next.

Get your free API key →
// this identifier, resolved live
GET /v1/timezones?iana=America/Santo_Domingo
{
"iana": "America/Santo_Domingo",
"utc_offset": "-04:00",
"abbreviation": "AST",
"observes_dst": false,
"country": "DO"
}