AMST — Amazon Summer Time
See what AMST means, its UTC-3 offset, how it relates to daylight saving time, and compare it with other time zones.
How to Convert AMST to Other Time Zones
Open the AMST converter page: Go to https://www.xconvert.com/time-converter/amst-time-zone to load the visual comparison grid with AMST (Amazon Summer Time) already shown as the reference row. This page is useful when you need to line up work in northern and western Brazil with other regions, such as scheduling a supplier call, checking a travel connection, or coordinating support coverage across South America and North America.
Add comparison cities: Click “+ Add City” and search for cities that matter to your schedule, such as São Paulo for Brazil headquarters coordination, New York for US client calls, or London for finance and logistics teams. This is especially practical for companies handling cross-border retail, agribusiness, aviation, or remote operations, because AMST is UTC-3 during summer time, the same clock offset used by several other South American zones at certain times of year.
Select a time range on the grid: Click “Select” to enter selection mode, then drag across the AMST row to highlight a meeting window, such as 9:00 AM to 11:00 AM AMST. That selection lets you instantly see the corresponding local times in the other rows—for example, a morning block in AMST may line up with the same clock time in São Paulo when Brasília Time is also UTC-3, but it can appear as one or more hours different from places observing different seasonal rules, which is critical when confirming whether a handoff or client call lands inside normal business hours.
Export and share the result: After selecting a range, use the export options shown by the tool: ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link. These options are useful when you want to send a confirmed AMST-based meeting to a distributed team so each person sees the event in local time automatically, whether they are joining from Brazil, the US, or Europe.
About Amazon Summer Time (AMST)
AMST stands for Amazon Summer Time. Its standard offset is UTC-3:00, meaning locations using AMST are 3 hours behind Coordinated Universal Time in sign convention terms (UTC-03:00) and 1 hour ahead of Amazon Standard Time (AMT, UTC-4:00).
Amazon Summer Time was historically used in parts of the Brazilian Amazon region during daylight saving time. In practice, it applied to Brazilian states in the Amazon time zone when Brazil’s DST rules advanced clocks by one hour for the summer season, shifting those areas from AMT (UTC-4) to AMST (UTC-3).
The time zone is tied to western and central parts of Brazil, not to the entire Amazon rainforest across South America. Although Brazil is the country associated with AMST, usage has been limited and policy-dependent because Brazil abolished nationwide daylight saving time in 2019, so AMST is now mainly encountered in historical records, legacy systems, archived schedules, and older software time-zone references.
Relative to UTC, AMST is straightforward: when it is 12:00 UTC, it is 09:00 AMST. That makes AMST share the same numerical offset as several other abbreviations listed at UTC-3, including BRT, ART, UYT, CLST, FKST, and PMST, but those abbreviations refer to different countries or seasonal rules, so the abbreviation itself still matters when interpreting old timestamps or legal records.
AMST and Daylight Saving Time
AMST is a daylight saving time designation, not a year-round base time zone. It represents the summer-time version of Amazon Standard Time (AMT), so when daylight saving time was in effect, clocks moved forward by 1 hour, changing from UTC-4 to UTC-3.
In Brazil’s former DST system, Amazon-region areas that observed the change typically switched from AMT to AMST in October or November and returned from AMST back to AMT in February. Under the last national daylight saving schedule used before abolition, clocks advanced at 00:00 local time on 4 November 2018 and moved back at 00:00 local time on 17 February 2019, although not every Brazilian state participated.
For the current year, 2026, there are no official AMST daylight saving transition dates, because Brazil does not currently observe daylight saving time. That means there is no active switch to AMST in 2026, and no scheduled return from AMST to AMT; if you see AMST in software, it is usually a historical label or a database artifact rather than a currently observed civil time.
This distinction matters for real scheduling. If you are planning flights, remote team meetings, or shipment cutoffs involving Brazil, you should verify whether the location currently uses standard local time year-round rather than assuming an older AMST label still applies.
Frequently Asked Questions
What does AMST stand for?
AMST stands for Amazon Summer Time. It was the daylight saving version of Amazon time used in parts of Brazil, shifting the local clock from UTC-4 to UTC-3 during the summer season when DST rules were active.
Is AMST the same as GMT?
No, AMST is not the same as GMT. GMT is UTC+0, while AMST is UTC-3, so AMST is 3 hours behind GMT; for example, when it is 3:00 PM GMT, it is 12:00 PM AMST.
Which cities use AMST?
AMST was associated with parts of Brazil’s Amazon time region, rather than a broad list of globally recognized standalone cities using the abbreviation today. Because Brazil ended daylight saving time in 2019, AMST is now mostly seen in historical schedules, archived timestamps, and legacy timezone databases, not as an actively used civil time in current city clocks.
What is the UTC offset for AMST?
The UTC offset for AMST is UTC-3:00. That means local AMST time is three hours behind UTC, so 18:00 UTC converts to 15:00 AMST.
When does AMST change?
Historically, AMST changed when daylight saving time started or ended in the relevant Brazilian region. The last nationwide Brazilian DST cycle began on 4 November 2018 and ended on 17 February 2019, and since Brazil no longer observes DST, there is no current annual AMST change date.
Is AMST still used in Brazil today?
In normal current civil timekeeping, no, AMST is not actively used today because Brazil abolished daylight saving time in 2019. You may still encounter it in old airline itineraries, server logs, calendar exports, or software libraries that preserve historical timezone abbreviations.
Is AMST the same as BRT or ART?
AMST shares the same UTC-3 offset as BRT and ART, but they are not the same label or the same legal time regime. BRT usually refers to Brasília Time in Brazil and ART to Argentina Time; identical offsets do not mean identical DST histories, jurisdictions, or transition rules.
Why does AMST appear in old calendar or system data?
AMST often appears in old data because timezone databases preserve the exact abbreviation that applied at the time an event was created. If a meeting, flight segment, or log entry was recorded during a period when a Brazilian Amazon-region location was on summer time, the system may keep AMST even though that abbreviation is no longer used in current everyday practice.