GMT to SST Converter
Convert time between Greenwich Mean Time (GMT) and Samoa Standard Time (SST)
Greenwich Mean Time (GMT)
Samoa Standard Time (SST)
Time Difference
Samoa Standard Time (SST) is 0 hours ahead of Greenwich Mean Time (GMT)
Select Date
Select Time
Quick Reference
| GMT | SST |
|---|---|
| 03:00 | 15:00 |
| 05:00 | 17:00 |
| 07:00 | 19:00 |
| 09:00 | 21:00 |
| 11:00 | 23:00 |
| 13:00 | 01:00 |
| 15:00 | 03:00 |
| 17:00 | 05:00 |
| 19:00 | 07:00 |
| 21:00 | 09:00 |
| 23:00 | 11:00 |
| 01:00 | 13:00 |
Top 10 Most Common Time Zones
| Abbreviation | Full Name | UTC Offset | Typical Use |
|---|---|---|---|
| UTC | Coordinated Universal Time | UTC ±0 | Global reference standard (servers, logs, APIs) |
| EST / EDT | Eastern (US) Time | UTC −5 / −4 | New York, Toronto — North American business hub |
| CST / CDT | Central (US) Time | UTC −6 / −5 | Chicago, Dallas — US central business region |
| PST / PDT | Pacific (US) Time | UTC −8 / −7 | San Francisco, Los Angeles — tech industry standard |
| GMT / BST | Greenwich Mean / British Summer Time | UTC 0 / +1 | UK, used globally as a reference with UTC |
| CET / CEST | Central European (Summer) Time | UTC +1 / +2 | Paris, Berlin, Amsterdam — EU business core |
| IST | India Standard Time | UTC +5:30 | India — major IT & outsourcing region |
| CST | China Standard Time | UTC +8 | Beijing, Shanghai — East Asia business hub |
| JST | Japan Standard Time | UTC +9 | Tokyo — finance & tech hub |
| AEST / AEDT | Australian Eastern (Daylight) Time | UTC +10 / +11 | Sydney, Melbourne — APAC regional business |
Why Time Zone Abbreviations Are Ambiguous
Unlike standardized identifiers (like America/New_York or Europe/London from the IANA tz database), abbreviations such as "CST" or "IST" are not globally unique. They can refer to different time zones depending on context — country, region, or even time of year (due to daylight saving time).
Common Ambiguous Time Zone Abbreviations
| Abbrev. | Common Meaning(s) | UTC Offset | Region(s) |
|---|---|---|---|
| CST | Central Standard Time / China Standard Time / Cuba Standard Time | UTC−6 / UTC+8 / UTC−5 | North America, China, Cuba |
| IST | Indian Standard Time / Irish Standard Time / Israel Standard Time | UTC+5:30 / UTC+1 / UTC+2 | India, Ireland, Israel |
| AST | Atlantic Standard Time / Arabia Standard Time | UTC−4 / UTC+3 | Caribbean, Canada, Middle East |
| PST | Pacific Standard Time / Philippine Standard Time | UTC−8 / UTC+8 | North America, Philippines |
| EST | Eastern Standard Time (North America / Australia) | UTC−5 / UTC+10 | North America, Australia |
✅ Best Practice
To avoid ambiguity, always:
- Use IANA tz identifiers — e.g.,
America/New_Yorkinstead of "EST" - Specify UTC offset explicitly — e.g.,
UTC−5when abbreviations must be used - Include the full timezone name — e.g., "Eastern Standard Time (EST)" with UTC offset
About GMT to SST Time Conversion
Converting time between Greenwich Mean Time (GMT) and Samoa Standard Time (SST) bridges the prime meridian and the South Pacific. GMT is UTC+0, while SST is UTC-11 and stays constant year-round (American Samoa does not observe daylight saving time). That makes SST 11 hours behind GMT during the UK winter — from the last Sunday in October to the last Sunday in March. From late March to late October the UK shifts to BST (UTC+1) and the gap widens to 12 hours.
This converter uses the IANA timezone database to handle UK DST transitions automatically. Whether you're booking a call between London or Dublin and Pago Pago, coordinating with year-round GMT users in Iceland or West Africa, or scheduling against UTC-aligned reference times, the tool removes the manual offset arithmetic.
Common Use Cases for GMT to SST Conversion
Business & Work
- Scheduling video calls between London, Dublin, or Reykjavík and American Samoa in winter
- Coordinating UK–Pacific and West Africa–Pacific remote team handoffs
- Aligning with GMT-anchored reference times for shipping, aviation, or scientific work
Personal & Travel
- Calling family in American Samoa from the UK or Ireland during winter
- Planning flight connections via Los Angeles or Auckland from London
- Coordinating live broadcasts and watch parties across hemispheres
Time Zone Information
Greenwich Mean Time (GMT)
- UTC Offset: UTC+0 (UTC+1 during BST in the UK)
- IANA Timezone: Europe/London
- Daylight Saving: GMT applies in the UK during winter; switches to BST (UTC+1) late March to late October. Iceland and several West African countries stay on GMT year-round.
- Major Cities: London, Dublin, Reykjavík, Lisbon, Accra
- Coverage: United Kingdom in winter, Iceland and parts of West Africa year-round
Samoa Standard Time (SST)
- UTC Offset: UTC-11
- IANA Timezone: Pacific/Pago_Pago
- Daylight Saving: None - American Samoa does not observe daylight saving time
- Major Cities: Pago Pago, Tafuna, Nu'uuli, Faleniu, Aua
- Coverage: American Samoa and Midway Atoll
Quick Reference: GMT to SST
Remember: SST is 11 hours behind GMT. From late March to late October the UK shifts to BST (UTC+1) and the gap becomes 12 hours; Iceland and several West African countries stay on GMT year-round.
Frequently Asked Questions
What is the time difference between GMT and SST?
Greenwich Mean Time (GMT) is UTC+0, while Samoa Standard Time (SST) is UTC-11. SST is 11 hours behind GMT. When it is 12:00 PM in London, it is 1:00 AM in Pago Pago.
When does this GMT to SST conversion apply?
GMT applies in the UK from the last Sunday in October to the last Sunday in March. From late March to late October the UK shifts to BST (UTC+1) and the gap widens to 12 hours. Iceland and several West African countries (Ghana, Senegal, Mali) stay on GMT year-round. American Samoa stays on SST (UTC-11) year-round.
How does the time difference change throughout the year?
For UK-based GMT users the gap is 11 hours in winter and 12 hours during BST in summer. For year-round GMT regions (Iceland, parts of West Africa) the gap is always 11 hours. American Samoa never observes daylight saving.
What are the best times for GMT–SST business calls?
An 11-hour gap means business hours barely overlap. The most workable window is late evening GMT against early morning SST: 8:00–10:00 PM GMT is 9:00–11:00 AM SST the same day.
Which countries and regions use SST?
Samoa Standard Time (UTC-11) is used in American Samoa and the uninhabited Midway Atoll. The independent state of Samoa is on UTC+13, on the opposite side of the international date line. Major American Samoa locations include Pago Pago, Tafuna, and Nu’uuli.
Which countries and regions use GMT?
Greenwich Mean Time is used in the UK during winter, and year-round in Iceland and parts of West Africa (Ghana, Senegal, Mali, Burkina Faso, Liberia). Portugal also uses GMT in winter. Major cities include London, Dublin, Reykjavík, Lisbon, and Accra.
Pro Tips
- • SST is 11 hours behind GMT — close to half a day, but both sides usually share the same calendar day.
- • American Samoa never observes daylight saving, so any seasonal shift comes from the UK side switching between GMT and BST.
- • Iceland and several West African countries stay on GMT year-round, while the UK uses GMT only in winter.
- • Late evening GMT and morning SST is the most workable overlap window for live calls.
- • During UK summer (late March to late October) the UK is on BST (UTC+1) and the gap becomes 12 hours.
- • For one-off calls, double-check the IANA zones (Europe/London or relevant African/Atlantic/Reykjavik, Pacific/Pago_Pago) in your calendar tool.