Find the Cheapest 20TB NAS Drive Today
20TB NAS-rated CMR drives by price per TB
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The best 20TB NAS drives are NAS-rated CMR models. 20TB is a top-tier capacity for data hoarders, large Plex and media servers, surveillance and small-business archives that need the most storage per bay. At this capacity, rebuild time matters, so favour CMR drives and consider RAID 6 or SHR-2 for two-drive protection. The live table ranks current 20TB drives by price per terabyte.
Who a 20TB NAS drive suits
20TB is a top-tier capacity for data hoarders, large Plex and media servers, surveillance and small-business archives that need the most storage per bay. These are helium-filled enterprise and Pro drives, the densest you can reasonably buy for a home or SOHO NAS.
20TB is overkill for a small Plex library but ideal for a large 4K collection or a household that never wants to run out. Fewer, larger drives also leave bays free to expand later.
Where 20TB sits on the value curve
20TB carries a clear capacity premium per terabyte over mid-size drives, but it gives the highest density per bay, so it wins when you have limited bays and a lot to store. Seagate Exos is typically the cheapest route to this capacity; the Pro NAS ranges cost a little more for lower noise and NAS tuning.
For the lowest price per terabyte at 20TB, Seagate Exos is usually the value pick, with WD Red Pro and IronWolf Pro costing a little more for lower noise and NAS tuning. The live table ranks them by current price per terabyte.
Usable capacity from 20TB drives
| Use case | Best choice | Why |
|---|---|---|
| 2x 20TB, RAID 1 / SHR | ~18TB usable | A mirror: survives one drive failure, half the raw capacity. |
| 4x 20TB, RAID 5 / SHR | ~55TB usable | Single parity: survives one failure, about 75% of raw. |
| 4x 20TB, RAID 6 / SHR-2 | ~36TB usable | Dual parity: survives two failures, the safer choice at high capacity. |
The 20TB buying note
At 20TB rebuild time and dual redundancy are the priority. A single-parity rebuild of a drive this large can run well over a day, so RAID 6 or SHR-2 (two-drive fault tolerance) is strongly advised over RAID 5. CMR is essential, and expect more noise and heat from these enterprise-class drives, which suit a cupboard or rack rather than a desk.
Available NAS-rated families at 20TB: 20TB comes from Seagate IronWolf Pro, WD Red Pro, Seagate Exos and Toshiba enterprise drives. There is no WD Red Plus or standard IronWolf at this size; everything here is a high-workload (300 to 550TB per year), 5-year-warranty class drive.
20TB NAS drives, by price per TB
Frequently asked questions
How many 20TB drives do I need for around 55TB usable?
Four 20TB drives in RAID 5 or Synology SHR give about 55TB usable after parity and overhead, with single-drive fault tolerance. Two 20TB drives in a mirror give about 18TB. For two-drive protection, four in RAID 6 or SHR-2 give about 36TB.
Is 20TB too much for a home NAS?
Not if you store a large 4K media library, run surveillance, or want maximum density per bay. 20TB gives the best capacity per bay; for light backup-only use, an 8TB to 12TB drive is cheaper per terabyte.
What is the cheapest 20TB NAS drive?
For the lowest price per terabyte at 20TB, Seagate Exos is usually the value pick, with WD Red Pro and IronWolf Pro costing a little more for lower noise and NAS tuning. The live table ranks them by current price per terabyte.
Does a 20TB drive need RAID 6 instead of RAID 5?
It is strongly advised. Rebuilding a failed 20TB drive can take more than a day, and RAID 5 has no protection during that window. RAID 6 or Synology SHR-2 keeps a second parity drive so the array survives a second failure mid-rebuild.