Western Digital · NAS
WD121KFBX
WD Red Pro 12TB
SATA 6Gb/s · 3.5-inch · CMR
Exact Amazon US product
$698.00
View on Amazon US ↗New listing · ASIN B07RTMPWD8
Price as of Sep 12, 2026 11:48 UTC
The Western Digital WD121KFBX is a 12TB WD Red Pro hard drive for NAS storage, using SATA 6Gb/s in a 3.5-inch form factor.
Manufacturer specifications
| Model number | WD121KFBX |
|---|---|
| Nominal capacity | 12 TB · 12000 GB |
| RPM | 7200 |
| Interface | SATA 6Gb/s |
| Recording | CMR |
| Cache (MB) | 256 |
| Form factor | 3.5-inch |
| Workload rating (TB/year) | 550 |
| Physical sector size (bytes) | 4096 |
| Manufacturer limited warranty | 5 years (eligible new drives) |
| Sustained transfer (up to MB/s) | 240 |
Source: Western Digital WD Red Pro manufacturer datasheet. Reviewed 2026-08-21. Published specifications, not our benchmark results.
What the specifications mean
- CMR recording is specified for this exact model. Check enclosure support and workload limits before installing it in an array.
- Up to 240 MB/s sustained transfer, as specified by the manufacturer. This is not a measured game-loading or random-I/O result.
- 550 TB/year workload rating. This is a workload limit, not a promise of drive lifespan or a backup guarantee.
Before ordering
Match WD121KFBX, 12TB and SATA 6Gb/s against the selected offer. Check your system’s exact-model compatibility list and the seller’s warranty and return terms.
Amazon US listings
Exact model matches on Amazon.com. A verified ASIN identifies the product; it does not guarantee current stock. Check the selected variant, condition and seller.
Amazon US · ASIN B07RTMPWD8
$698.00 · as of Sep 12, 2026 11:48 UTC
Amazon US · ASIN B0893PDHFC
$1,101.00 · as of Sep 12, 2026 11:48 UTC
Amazon US · ASIN B07WYF7YXL
$1,281.90 · as of Sep 12, 2026 04:49 UTC
Amazon US · ASIN B07RTMPWD8
$399.99 · as of Sep 12, 2026 11:48 UTC
Same-capacity alternatives with Amazon US links
These models share the drive type, interface class and capacity. Compare their specifications and your system requirements before choosing a replacement.
Seagate · IronWolf
ST12000VNZ008
12TB · SATA 6 Gb/s · CMR
Compare with WD121KFBX →View on Amazon US ↗ASIN B08147LZFD · Check price and conditionSeagate · IronWolf
ST12000VN0007
12TB · SATA 6 Gb/s
Compare with WD121KFBX →View on Amazon US ↗ASIN B075X181C5 · Check price and conditionSeagate · IronWolf Pro
ST12000NE0007
12TB · SATA 6 Gb/s
Compare with WD121KFBX →View on Amazon US ↗ASIN B075X23774 · Check price and conditionWD121KFBX questions answered
Is WD121KFBX CMR or SMR?
The manufacturer lists CMR recording for WD121KFBX. Other models and capacities in the same family can differ.
What connection does WD121KFBX need?
WD121KFBX uses SATA 6Gb/s and a 3.5-inch form factor. Match both with the computer, controller or enclosure. An M.2 slot, 2.5-inch bay and 3.5-inch bay are not interchangeable.
How much usable space does WD121KFBX provide?
Its nominal capacity is 12000 GB, approximately 11175.9 GiB before formatting. The filesystem, reserved space and any RAID redundancy reduce usable capacity further.
What warranty is listed for WD121KFBX?
Manufacturer specification: 5 years (eligible new drives). A renewed, used, OEM or imported offer can have different coverage. Check the serial number and seller terms before buying.