While real-world usage varies, the theoretical speed limits set by the JEDEC Solid State Technology Association highlight the gap between the two.
| Feature | eMMC 5.1 | UFS 2.2 | | :--- | :--- | :--- | | Interface | Parallel (8-bit) | Serial (Lanes) | | Theoretical Max Read | Up to 250 MB/s | Up to 850 MB/s | | Theoretical Max Write | Up to 125 MB/s | Up to 460 MB/s | | Full Duplex | No (Half-Duplex) | Yes (Full-Duplex) | | Command Queue | HQ Command Queue | Multi-Circular Queue |
The Takeaway: UFS 2.2 is roughly 2x to 3x faster in sequential read speeds compared to eMMC 5.1. In practical terms, a phone with UFS 2.2 will boot up faster, install apps quicker, and copy large video files in a fraction of the time.
It is worth noting that UFS 2.2 introduced the Write Booster feature. This uses a small portion of high-speed SLC (Single-Level Cell) cache to absorb incoming data before writing it to the slower TLC/QLC NAND. This allows UFS 2.2 to occasionally spike to speeds exceeding 1 GB/s for short bursts, leaving eMMC 5.1 in the dust.
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A specific advantage of UFS 2.2 over older UFS standards (and eMMC) is the optional Write Booster.
The most significant difference between these two standards is not just raw speed, but how data moves.
Demand UFS 2.2 if:
UFS uses a "serial" interface, similar to the technology used in modern SSDs in laptops. It features "Full Duplex" communication.
Because UFS 2.2 supports Command Queuing, it can process multiple requests at once. On an eMMC 5.1 device, opening a heavy app like Instagram or Genshin Impact involves a queue of requests waiting in line. On UFS 2.2, those requests are processed in parallel. The result: apps open 30–50% faster.