Fresh/Last checked Sep 26, 12:43 PM·Updated daily
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Best 20TB Hard Drives by Price per TB

A 20TB drive is worth it for the most capacity per bay if your array has dual parity or a real backup — pick a new NAS- or enterprise-class drive for 24/7 use, and use the ranking below to find today's lowest price per TB.

A 20TB drive is what you buy when you run out of bays before you run out of data. NAS owners, video editors archiving projects, and media collectors use it to add capacity without adding hardware. The list below ranks today's Amazon offers for exactly 20TB — internal and external, new and renewed — by price per TB, re-ranked on every snapshot refresh.

The honest catch is the rebuild window. Writing 20TB once at top sustained speed takes about 19 to 20.5 hours, and a real RAID rebuild takes longer because the array keeps serving data and the inner tracks are slower. A failed 20TB drive leaves an array exposed for most of a day or more. That doesn't make 20TB a bad buy — it makes dual parity or a separate backup part of the purchase.

  1. Seagate IronWolf Pro, 20 TB, Enterprise NAS Internal HDD –CMR 3.5 Inch, SATA 6 Gb/s, 7,200 RPM, 256 MB Cache for RAID Network Attached Storage (ST20000NT001)

    $719.99 · $36.00/TB as of Sep 26, 12:43 PM

    Ranks #1 at $36.00/TB — 10% below the typical HDD of similar size. New condition, SATA, 3.5".

  2. Seagate 20TB Exos Enterprise Hard Drive | SATA (ST20000NM002H)

    $799.99 · $40.00/TB as of Sep 26, 12:43 PM

    Ranks #2 at $40.00/TB. New condition, SATA.

  3. Western Digital 20TB WD Red Pro NAS Internal Hard Drive HDD - 7200 RPM, SATA 6 Gb/s, CMR, 512 MB Cache, 3.5" - WD202KFGX

    $849.57 · $42.48/TB as of Sep 26, 12:43 PM

    Ranks #3 at $42.48/TB — 6% above the typical HDD of similar size. New condition, SATA, 3.5".

  4. Toshiba N300 20TB NAS 3.5-Inch Internal Hard Drive - CMR SATA 6 GB/s 7200 RPM 512 MB Cache - HDWG62AXZSTA

    $899.95 · $45.00/TB as of Sep 26, 12:43 PM

    Ranks #4 at $45.00/TB — 12% above the typical HDD of similar size. New condition, SATA, 3.5".

Compare live hard disk prices for all matching deals →

What to look for

Buy the class that matches 24/7 duty. Desktop-class drives are rated for 120 TB of writes a year, limited power-on hours, and a 2-year warranty; entry NAS-class for 180 TB and 3 years; pro NAS and enterprise-class for 550 TB and 5 years. A 20TB drive in an always-on NAS belongs in the last group, and the longer warranty covers more of its working life.

Weigh the error-rate spec more heavily at this size. Pro NAS and enterprise drives are rated for 1 unrecoverable read error per 10^15 bits read; many desktop and entry-NAS drives are rated 1 per 10^14, which is about 12.5 TB. A rebuild reads every surviving drive end to end, so at 20TB per drive the stricter rating is worth a little more per TB. These are worst-case specs, not predictions, but they point the same way.

Choose by model record, not brand or capacity. Backblaze's fleet data shows failure rates vary more by model than by size — at the same capacity, one model can fail over ten times as often as another — while its drives of 20TB and up averaged under 1% a year. Recording technology is a non-issue here: current 20TB drives in Seagate's consumer and NAS lines and WD Red Pro are CMR, so SMR slowdowns don't apply.

FAQ

Is a 20TB hard drive worth it?

Yes, if you want the most capacity per bay and your setup can survive a long rebuild. Run it with dual parity or keep a separate backup. The trade-off is concentration: one failure puts 20TB at risk until the rebuild finishes.

How long does it take to rebuild a 20TB drive in RAID?

At least 19 to 20.5 hours — that is one full write at a top sustained speed of about 270 to 290 MB/s. Real rebuilds take longer because the array keeps serving data and the inner tracks are slower, so plan for a day or more.

How much does a 20TB hard drive cost?

It moves with the market, so this page ranks live offers by price per TB instead of quoting a number. Compare the price per TB and the condition on each entry; a renewed drive and a new one can be close on price but far apart on warranty.

Should I buy a 20TB external or internal drive?

Internal for a NAS or array; external for a standalone archive or backup you plug in when needed. Removing the drive from an external enclosure voids the maker's warranty, and makers don't disclose which drive is inside, so an external is a poor way to buy a NAS drive.