Western Digital · Ultrastar DC HC550 · 512e
WUH721816ALE6L4 is Western Digital Ultrastar DC HC550 16TB SATA-6G. 3 of its 4 segments are defined in Western Digital's published documentation and decoded below; the rest are not publicly documented and are marked as such. No live listings right now - the reference material below still applies.
| Segment | What it means | Source |
|---|---|---|
| WUH | Ultrastar DC HC series, helium-filled. | Western Digital |
| 721816 | Capacity and generation field. The leading digits encode capacity in the family's own scheme; see the specification sheet linked below for the exact model. | Western Digital |
| ALE | SATA 6Gb/s interface, 512e sector format. | Western Digital |
| 6L4 | Western Digital does not publicly document this segment. | not documented |
We decode only what the manufacturer documents. There is a large body of community knowledge about the undocumented segments above, much of it probably right, and none of it published by Western Digital - so it does not appear in this table. A reading nobody can check does not belong in a column headed “what it means”. Grammar reference: Western Digital - Ultrastar model-number nomenclature.
WUH721816ALE6L4 is Western Digital Ultrastar DC HC550, a 16TB hard drive on SATA-6G. It uses the 512e sector format, which decides whether it will drop into an array or controller expecting the other one.
We hold no live listing against this exact part number at the moment. 1 sibling part number is documented below - these are the numbers most often mistaken for this one, and the table marks which fields actually differ.
| Manufacturer | Western Digital |
| Family | Ultrastar DC HC550 |
| Capacity | 16TB |
| Interface | SATA-6G |
| Sector format | 512e |
| Product class | HDD |
These are the part numbers most often confused with WUH721816ALE6L4. The differences below come from the same vendor documentation as the decode above - where a field is not documented, the row leaves it blank rather than guessing.
| Part number | Capacity | Interface | Format | |
|---|---|---|---|---|
| WUH721818ALE6L4 | 18TB | SATA-6G | 512e | reference |
Amber cells differ from WUH721816ALE6L4; grey cells match it.
No live listings for WUH721816ALE6L4 right now. We are not going to fill this space with something else and call it a match. The decode, specifications and sibling table above are the reference answer for this part number and remain accurate whether or not anyone is selling one today. If you need the capacity rather than this specific part, the alternatives below are what is actually buyable.
A manufacturer part number does not imply a manufacturer warranty, and this is where part-number buyers lose the most money. OEM stock, integrator pulls and gray-market units all reach the market under the maker's own numbering. Retailers selling them sometimes state plainly that the manufacturer warranty is none; others simply do not mention it, which is not the same as it being covered.
Coverage attaches to the individual unit and its serial number, not to the part number. That means the only reliable answer comes from the manufacturer, about the specific drive you are being sold.
Ask the seller for the serial number before purchase, then enter it in Western Digital warranty checker. We link the tool rather than showing a result here, because the answer depends on the individual drive and only Western Digital can give it.
A seller warranty is a different promise from a different company. What each warranty tier actually covers · Verify on arrival
4 in-stock listings · same capacity, any part number · ranked by live cost per tb, refreshed every few hours
| Drive | Capacity | Interface | Recording | Condition | $/TB | Price | |
|---|---|---|---|---|---|---|---|
| Seagate IronWolf Pro 16TB NAS ST16000NE000 ST16000NE000 | 16TB | SATA-6G | CMR | REFURB | $28.12 | $450 | Buy |
| WD Ultrastar 16TB SAS WUH721816AL5205 WUH721816AL5205 | 16TB | SAS-12G | CMR | REFURB | $30.63 | $490 | Buy |
| Seagate SkyHawk AI 16TB ST16000VE000 ST16000VE000 | 16TB | SATA-6G | CMR | REFURB | $32.50 | $520 | Buy |
| WD WD Red Pro 16TB WD161KFGX WD161KFGX | 16TB | SATA-6G | CMR | REFURB | $36.25 | $580 | Buy |
Every 16TB drive we track, ranked by cost per terabyte.
WUH721816ALE6L4 is Western Digital Ultrastar DC HC550 16TB SATA-6G. 3 of its 4 segments are defined in Western Digital's own published documentation - the decode table on this page shows each one with the document that defines it. The remaining segments are not publicly documented, and we say so rather than repeating a community guess as fact.
Not necessarily, and the part number cannot tell you. Coverage depends on how the individual unit entered the market and whether it was registered, not on its model designation. OEM and gray-market stock reaches the market under manufacturer part numbers regularly and frequently carries no manufacturer warranty at all - some retailers print exactly that on the listing. Check the specific serial with Western Digital's own tool, linked in the warranty section on this page.
Both are in the Ultrastar DC HC550 range. The clearest difference is capacity - 16TB against 18TB. The variant table on this page lists every sibling we document with what differs.
We hold no live listing for this part number right now. That is the honest state rather than a broken page - this remains the reference answer for what WUH721816ALE6L4 is, how it decodes and which siblings it is confused with. The alternatives section below shows what is currently buyable at the same capacity.
Because more than one organisation names it. The manufacturer assigns a model number describing the product; a server vendor buying it in volume assigns its own spare-part number for its service catalogue; distributors sometimes add another. All identify the same physical drive, which is why one number returns listings that look like a different product. Our part number index explains the pattern per vendor.