Best 4TB NAS Drives UK 2026: CMR Picks by Price per TB
4TB NAS-rated CMR drives by price per TB
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The best-value 4TB CMR NAS drive right now is the WD Red Plus 4TB (ASIN B0GFFK7RSG) at around £146.99, working out to £36.75/TB at last check on 24 July 2026. It undercuts the Seagate IronWolf range by a small margin whilst offering the same 5400rpm CMR reliability that NAS vendors expect for RAID rebuilds. The Skyhawk at £146.26 is marginally cheaper still, but it's a surveillance drive tuned for continuous video writes rather than multi-user NAS access, so the WD Red Plus is the sounder pick for anyone building or expanding a home or small office NAS pool.
Best 4TB NAS drives
All the drives below are genuine CMR, which matters enormously at 4TB where SMR models still lurk in some retail listings. Prices and £/TB are indicative, last checked 24 July 2026.
Which 4TB drive should you buy
Choose WD Red Plus if
- You want the lowest £/TB genuine NAS CMR drive on this list
- Your NAS runs 1-4 bays and workloads are typical home or small office file serving
- You don't need 7200rpm speed and prefer lower noise and power draw
Choose IronWolf Pro if
- You run a busy multi-user NAS or need faster rebuild and resync times
- You want the higher workload rating and rotational vibration sensors for larger bay counts
- You're happy paying roughly £23 more per drive for the performance and endurance headroom
Who actually needs 4TB in 2026
4TB sits at an awkward point in the NAS capacity ladder now. It suits 2-bay NAS units used for backups, media libraries under a few thousand films or a modest Plex collection, and small office document stores where the total pool doesn't need to exceed 8TB usable in RAID 1, or perhaps 12TB in a 4-bay RAID 5 array. If you're starting a NAS build from scratch in 2026 and expect your storage needs to grow, it's worth comparing the cost per TB against 6TB and 8TB drives, because the price gap per terabyte often narrows sharply above 4TB. But for a fixed, modest capacity need, or as a matched pair for redundancy, 4TB drives remain sensible and this list gives you genuine CMR options throughout.
CMR versus SMR is not a minor technical footnote at this capacity, it's the difference between a NAS that rebuilds reliably and one that can fail catastrophically mid-rebuild. Shingled Magnetic Recording (SMR) drives write data in overlapping tracks to boost areal density cheaply, but this makes random writes and RAID resync operations dramatically slower and, in degraded array scenarios, can push rebuild times long enough that a second drive failure becomes a real risk. Every drive listed here is CMR (Conventional Magnetic Recording), which is exactly what you want. Seagate IronWolf, IronWolf Pro, WD Red Plus and Toshiba N300 are all designed and validated for continuous NAS operation and RAID use, whereas the Skyhawk and Purple ranges are surveillance-optimised, built for sustained sequential writes from camera feeds rather than the mixed random I/O typical of file serving or virtualisation workloads.
A rebuild safety note worth reading before you buy
If you're populating a multi-bay NAS with 4TB drives for RAID 5 or RAID 6, buy from more than one batch or even mix manufacturers slightly, rather than filling every bay with drives from the same production run. Identical drives bought together tend to fail in the same rough timeframe under similar stress, and losing a second drive during a rebuild window is the classic RAID horror story. IronWolf Pro and Red Plus both carry solid workload ratings for this kind of use, but no drive avoids batch-correlated failure risk, that's a purchasing and array-planning decision, not a drive spec one.
4TB NAS drives, by price per TB
Prices are indicative — last checked 8 September 2026, from Amazon.co.uk. They are not live; check the current price on Amazon before buying. Best £/TB is the lowest at last check.
Frequently asked questions
Is WD Red Plus 4TB actually CMR, given WD's past SMR controversy?
Yes. WD Red Plus has been CMR-only since the backlash over SMR drives being sold without disclosure in the original WD Red line. WD Red Plus and WD Red Pro remain CMR; only the base WD Red (non-Plus) line uses SMR at smaller capacities, and it's not on this list.
Should I use Seagate Skyhawk or WD Purple drives in a NAS instead of IronWolf?
You can, but it's not ideal. Skyhawk and Purple are built for surveillance DVR/NVR workloads, sustained sequential writes from cameras, not the random read/write mix of typical NAS file serving. They'll work, but IronWolf, IronWolf Pro or WD Red Plus are the better-matched choice for actual NAS duty.
Is IronWolf Pro worth the extra roughly £23 over standard IronWolf at 4TB?
For a busy multi-bay NAS with several simultaneous users or frequent large file transfers, yes, the 7200rpm speed and higher workload rating help. For a 2-bay home NAS doing light backups, standard IronWolf or WD Red Plus is perfectly adequate and better value.
What's the safest RAID level for 4TB drives in a 4-bay NAS?
RAID 5 across four 4TB drives gives roughly 12TB usable with single-drive fault tolerance, but rebuild times on larger arrays can take many hours, during which a second failure is catastrophic. RAID 6 or RAID 10 offer more protection at the cost of usable capacity, worth considering if the data matters.
Are these prices likely to change?
Yes, these figures were last checked on 24 July 2026 and are indicative only, not real-time. Always check the current price at the retailer before buying, as HDD pricing shifts with demand and stock levels.