Which 20 TB hard drive should you buy?

What these specifications actually mean

At a single capacity the price differences between drives are small and the specification differences are not, which inverts how most people shop. Sorting by price per terabyte is the right first move only once you have filtered to the drives that suit the job, because the cheapest 20 TB drive and the most expensive one are frequently not substitutes at all.

The first filter is recording technology. 22 of these 22 use conventional recording, where tracks do not overlap and a rewrite costs no more than a first write. That is what an array needs: a rebuild reads and writes the entire drive, and a shingled drive can slow by an order of magnitude doing it. For a single backup target written once and read occasionally, shingled recording is free density and a reasonable buy.

The second is the rated workload, which is the figure most buyers skip and most warranty disputes turn on. The ST20000NT001 is rated highest here at 550 TB a year. It is a warranty envelope rather than a performance ceiling: the drive keeps working past it, but consistently exceeding it gives the maker grounds to decline a claim. A home NAS doing media and nightly backups rarely passes 20 TB a year; a multi-camera surveillance recorder passes it easily.

The third is warranty length, which is a reasonable proxy for how hard the maker expects the drive to be used. The WD201KFGX carries the longest cover at 5 years. Remember that the term runs from manufacture rather than purchase unless you register proof, which quietly costs several months on a drive that sat in a warehouse.

Only after those three does price per terabyte decide anything. At 20 TB the spread between the cheapest and dearest suitable drive is usually small enough that warranty and workload rating are worth more than the saving, and our cost per TB calculator will show you both the advertised and the usable figure for any specific pair.

What it suits, and what it does not

For a NAS or RAID array: take a conventional-recording drive with a stated workload rating. ST20000NT001, MG10ACA20TA, MG10ACA20TAY, MG10ACA20TE qualify here.

For a single backup or archive drive: the constraints relax considerably. Nothing is rebuilding, so shingled recording costs you little and the cheapest per terabyte is usually the right answer.

For surveillance: the workload rating is the deciding number, because cameras write continuously rather than in bursts. Prefer a drive rated at 180 TB a year or more, and size the array so no single drive carries the whole write load.

For a desktop: almost any of these will do, and 20 TB is likely more than a desktop needs. The better question is whether the data should be on spinning storage at all, which our flash versus hard drive comparison covers.

What to do with this

1. Filter to conventional recording first if the drive is going into an array; check with our model number decoder.
2. Check the rated workload against how hard you will actually drive it, not against how hard you imagine you will.
3. Look up measured failure rates per model on our AFR table, reading the drive-days column before the rate.
4. Sort the live table above by price per terabyte, but only among the drives that passed the first three filters.
5. Compare 20 TB against the capacity above and below on our price per TB page; the per-terabyte advantage of larger drives widened through 2026.
6. Register the warranty on arrival, since it runs from manufacture unless you file proof of purchase.