| £/TB | Price | Size | Tech | Form Factor | Condition | Description | Rating | Reviews | |
|---|---|---|---|---|---|---|---|---|---|
 | £34.17 | £615.00 | 18 TB | HDD | 3.5" | Renewed | ★★★★☆ 4.2 | 122 | |
 | £34.55 | £621.90-1.3% 24h | 18 TB | HDD | 3.5" | New | ★★★★☆ 4.2 | 200 | |
 | £34.72 | £625.00 | 18 TB | HDD | 3.5" | Renewed | ★★★★☆ 4.2 | 124 | |
 | £35.56 | £640.00 | 18 TB | HDD | 3.5" | New | ★★★★☆ 4.0 | 679 | |
 | £38.06 | £684.99 | 18 TB | HDD | 3.5" | New | ★★★★☆ 4.3 | 283 | |
 | £38.06 | £684.99 | 18 TB | HDD | 3.5" | New | ★★★★½ 4.5 | 49 | |
 | £45.77 | £823.81-8.2% 24h | 18 TB | HDD | 3.5" | New | ★★★★☆ 4.0 | 1,821 | |
 | £49.99 | £899.88 | 18 TB | HDD | 3.5" | New | ★★★★½ 4.6 | 79 | |
 | £190.76 | £3,433.69 | 18 TB | HDD | External | New | ★★★★☆ 4.1 | 24 |
Choosing an 18TB NAS drive
Today the best value is Seagate IronWolf Pro 18TB NAS HDD at £615.00 (£34.17/TB). At 18TB the enterprise drives — Seagate Exos, Toshiba MG and WD Ultrastar — are often cheaper per terabyte than the NAS-branded lines, and they carry 5-year warranties. The catch is noise and heat: they are built for server rooms, so a NAS that lives in a quiet room may be better with IronWolf Pro or Red Pro. Big drives also take a long time to rebuild after a failure (often a day or more), which is why RAID 6 or a second backup becomes important at this size.
- 2-bay, RAID 1 (mirror): 18TB usable from 2 × 18TB, about £1,230.00 in drives at today’s best price.
- 4-bay, RAID 5: 54TB usable from 4 × 18TB, about £2,460.00 in drives at today’s best price.
- 5-bay, RAID 5: 72TB usable from 5 × 18TB, about £3,075.00 in drives at today’s best price.
- 8-bay, RAID 6: 108TB usable from 8 × 18TB, about £4,920.00 in drives at today’s best price.
18TB NAS drives by family
| Family | Drives | Best £/TB | Best-value model |
|---|---|---|---|
| Seagate IronWolf Pro | 2 | £34.17/TB | Seagate IronWolf Pro 18TB NAS HDD |
| WD Red Pro | 2 | £45.77/TB | WD Red Pro 18TB NAS 3.5" Internal Hard Drive |
| Toshiba N300 | 2 | £38.06/TB | Toshiba N300 18TB Internal NAS Hard Drive |
| Seagate Exos | 2 | £34.55/TB | Seagate Exos X20 18TB Internal Hard Drive |
| WD Ultrastar | 1 | £190.76/TB | SanDisk Professional 18TB G-DRIVE PRO |
Buy drives from more than one batch when filling a multi-bay array, to cut the risk of two failing together. For the full picture see our NAS drive guide, SMR vs CMR and when to replace NAS drives, or compare every size on the NAS drive hub.
Frequently asked questions
How does disks.co.uk rank 18TB NAS drives?
We rank every 18TB NAS drives by real cost per terabyte (£/TB) — the live Amazon.co.uk price divided by capacity — so the best value appears at the top. Prices refresh several times a day from Keepa, with 24-hour movement and all-time-low flags.
What is the cheapest 18TB NAS drives right now?
The drive at the top of the table above is the cheapest of the 18TB NAS drives by £/TB today. At larger sizes the enterprise Exos, Toshiba MG and Ultrastar drives are often cheaper per terabyte than the NAS-branded lines; they are louder, but carry 5-year warranties.
Are all of these drives CMR?
The NAS-rated families listed here — IronWolf and IronWolf Pro, WD Red Plus and Red Pro, Toshiba N300 — and the enterprise drives all use conventional (CMR) recording. The one to watch is plain "WD Red" (no Plus or Pro) in the 2–6TB sizes, which is shingled (SMR) and a poor fit for RAID. See SMR vs CMR.
How many 18TB NAS drives do I need?
It depends on the bay count and RAID level: two drives in RAID 1 give you one drive's space with a full mirror; four in RAID 5 give three drives' worth and survive one failure. The section below works out usable space and cost at this size, and our NAS drive guide covers the choice in more detail.