Samsung is the best brand for customers who care about firmware updates. For one, Galaxy smartphones receive more Android OS upgrades than phones from other brands. Furthermore, Samsung is usually the first OEM to release new security patches, sometimes even ahead of Google.
Samsung also provides the ODIN tool for Galaxy smartphone users who prefer manual updates. And as many SamMobile readers know, official Samsung firmware files that can be used with ODIN are available for download on our website.
You've probably seen a firmware number before. They look confusing and seemingly random. But if you've wondered what those letters and numbers mean, we've got the answer.
Below, you will find a detailed explanation of what each letter and number in every Samsung firmware version means. With this information, Samsung's firmware versions will no longer look like strings of seemingly random characters. You'll be able to read the hidden meaning behind the apparent randomness and gain all the information you need at a glance.
Reading Samsung firmware numbers the easy way, in four segments
Each character contains specific bits of information about the firmware and the target device. The easiest way to understand Samsung's firmware number scheme is to break it down into four segments.
We'll use a recent Galaxy S24 Ultra firmware update as an example throughout this article. The firmware version in question is S928BXXS4AYA1. We'll break it down as follows: S928 – BXX – S4A – YA1.
You could cut Samsung firmware numbers in different segments. However, we chose this formula because we think it makes the most sense and it's easiest to remember. Each segment is defined by the type of information it pertains to, such as:
- The first segment (S928) represents the hardware.
- The next three (or four for USA unlocked) characters (BXX / U1UE) represent availability.
- The third batch of three characters (S4A) pertains to the contents of the update.
- And finally, the last three characters (YA1) reveal when the firwmare was built.
Remember that we're using this S928BXXS4AYA1 firmware number from the Galaxy S24 Ultra as a reference. However, this string of letters and numbers will vary based on each Galaxy device and update available.
Samsung firmware number segment 1 — S928 — device information
- (S)928 – BXX – S4A – YA1: The first character shows the Galaxy series. “S” is for the Galaxy S series (although it used to be “G” before the Galaxy S22 came along), “F” is for foldable devices, “E” stands for the Galaxy F family, and “A” represents the Galaxy A lineup, etc.
- S(9)28 – BXX – S4A – YA1: The second character in the firmware number loosely represents the price point of your Galaxy device. “9” is for top-tier phones like the Galaxy S24, Galaxy S25, the Galaxy Z Fold 6, and so on. A cheaper device, such as the Galaxy S24 FE, has model number (SM-)S721. “S7” labels this phone as an S-series device that's not necessarily cheap (7) but doesn't cost as much as a flagship (9). A 7 is also used to identify the Galaxy Z Flip series, which is priced way below the Galaxy Z Fold.
- S9(2)8 – BXX – S4A – YA1: The third character reveals the generation of the Galaxy device, but it can be a bit tricky. As some might recall, Samsung never had a Galaxy S11. The naming scheme jumped from Galaxy S10 to S20 a few years ago. Furthermore, the Galaxy S21 (G991) was a 9th generation flagship, so the Galaxy S22 series had to jump from a “9” to a “0” when it went on sale a year later. That is why the Galaxy S24 (a 12th-generation device) has S92 in its firmware, and the Galaxy S25 will always have S93 firmware. Another example is the Galaxy A series. The Galaxy A55 (SM-A556) is considered the fifth generation in its series ever since Samsung changed the naming scheme from “Galaxy A5” to “Galaxy A5x.”
- S92(8) – BXX – S4A – YA1: The fourth and last digit in the first segment has a different meaning for each Galaxy lineup. For flagships, it usually means that the higher the number, the larger the display. The Galaxy S24/S25, Galaxy S24+/S25+, and Galaxy S24 Ultra/S25 Ultra carry the numbers “1,” “6,” and “8,” respectively. For some (or older) phones, this character also shows whether the phone caps out at 4G LTE or has 5G capabilities. “0” and “5” are reserved for LTE devices, while 5G Galaxy phones can use characters such as “1,” “6,” and “8.”
Samsung firmware number segment 2 — BXX — market availability
- S928 – (B)XX – S4A – YA1: The first character in this segment corresponds to the market region where the Galaxy device and its firmware updates roll out. Sometimes, this letter changes based on whether or not the device is 5G capable. “F” and “B” denote international LTE and 5G models, respectively. “E” corresponds with Asian markets, although “N” is reserved for South Korea. “U” is for the USA, but unlocked Galaxy devices in the United States get an extra character — “U1.” Variations like “FN” and “FG” also exist in a few markets.
- S928 – B(XX) – S4A – YA1 These two grouped characters contain additional information about the specific variant of your device in your market. “XX” is associated with firmware for international and European devices. USA devices carry “SQ,” but USA-unlocked devices have the letters “UE.” You can always check which firmware version your Galaxy device has by opening the Settings app, then tapping “About phone” and “Software information.”
IMPORTANT: The first two segments in the firmware number of your Samsung Galaxy device will never change, no matter how many updates it receives. The rule when you install firmware updates manually is to never try to apply updates whose first seven (or eight for USA/FN/FG) characters in the firmware number don't match your current version.
Samsung firmware number segment 3 — S4A — the contents of the update
- S928 – BXX – (S)4A – YA1: This character is always either an “S” or a “U,” no matter which Samsung Galaxy phone or tablet you're using and where. It tells whether the current firmware update contains only a security patch “S” or if it brings additional features “U” aside from improved security and stability.
- S928 – BXX – S(4)A – YA1: This is the bootloader number for the firmware. A bootloader is a crucial bit of software that tells your Galaxy phone what programs to load at startup. It's analogous to the BIOS in Windows PCs. It's important to know that you can never roll back to a firmware update that has a bootloader version lower than your current one. In other words, the number “4” in the Galaxy S24 Ultra firmware version that we're using here as an example means the firmware contains bootloader version 4, and users cannot roll back to any update that has bootloader version 3 or lower.
- S928 – BXX – S4(A) – YA1: This character reveals how many major One UI and feature updates the device has received. Every new Galaxy device starts with an “A,” and this letter goes up one notch in the alphabet with every significant update or new version of One UI it picks up along the way. The Galaxy S24 Ultra shipped with Android 14 and One UI 6.1 (A). Once it receives Android 15 and One UI 7, the letter A will change to a B.
Samsung firmware number segment 4 — YA1 — the update's build history
- S928 – BXX – S4A – (Y)A1: The third-last character in Samsung's firmware number represents the year when the update was built. In Samsung's firmware number language, “U” was 2021, “V” was 2022, “W” was 2023, “X” was 2024, and “Y” is 2025. Broadly speaking, this character represents the year when the update was built.
- S928 – BXX – S4A – Y(A)1: Similarly, the second-last character coincides with the month when the firmware was completed — not when it was released. “A” is for January, which means that the letter “E” in our example represents May. There's always a chance that an update Samsung finalized in one month could go live the next, so the letter won't always match the current month. Likewise, this letter doesn't always match the security patch for the month. An update built in May can go live in June and contain an earlier security patch.
- S928 – BXX – S4A – YA(1): The last character in Samsung's firmware number scheme is a build identifier. This character can be a number and sometimes a letter. Every new update starts at build identifier “1” or “A.” It goes up a notch with every new build and resets to “1” or “A” with every new substantial firmware update released. A monthly firmware update with build identifier “8” doesn't mean it's the 8th build released in that month.Some builds can enter development and tick the build identifier, but the update might never be released to the public. That is why you might have build identifier “1” on your current firmware and receive a new update the same month with build identifier 8. Some updates don't see the light of day, but the build identifier changes with each one, regardless of availability.
We know keeping track of all these bits of information can be tricky, but you can always refer to this page for clarification. Just remember that the letters and numbers above are used as an example, and the guide uses a firmware version for the Galaxy S24 Ultra as a framework.
These letters and numbers themselves can be very different depending on your device. Nevertheless, their meaning is always the same across all Galaxy phones and tablets.
