Samsung firmware version numbers explained
A Samsung build number such as A546BXXUNGZJ5 is not random. Read it from the right – the last six characters
carry the information, whatever the length of the model code in front.
| Position (from the end) | Example | Meaning |
|---|---|---|
| 6th last | U | Update type: U = feature update (new functions, often a new Android or One UI version), S = security update only |
| 5th last | N | Bootloader (binary) bit: 0–9, then A = 10, B = 11 … N = 23. Decides whether you can downgrade. |
| 4th last | G | Major OS letter: increases with every big Android/One UI upgrade of this device |
| 3rd last | Z | Build year: … W = 2023, X = 2024, Y = 2025, Z = 2026 |
| 2nd last | J | Build month: A = January … L = December |
| last | 5 | Build number within that month |
The characters before that identify the model (A546B) and the region group (XX = open market).
PDA, CSC and modem
The complete firmware version has three or four parts: PDA/CSC/MODEM[/BOOTLOADER], for example
A546BXXUNGZJ5/A546BOXMNGZJ5/A546BXXUNGZJ5.
- PDA – the Android system build. This is what our model pages list.
- CSC – the region package.
OXMis a multi-CSC group covering many countries. - Modem – the radio firmware. It can lag behind the PDA by one build.
Why the date in the build number can differ from the release date
The year and month letters show when Samsung built the firmware. Rollout often starts weeks later – a build marked December may reach users in January. Our “” column shows when the build first appeared on Samsung's servers.