Hard drive specifications, compared against the category
Capacity is the only specification on a hard drive that changes what you pay per terabyte, and it is the one figure no listing states in those terms. This site works it out for every drive in the corpus.
Spindle speed is the same across the whole market; capacity is what moves the price.
Buyers are told to compare RPM, and almost every drive here turns at the same speed, so the comparison decides nothing. What does vary, steeply, is the price per terabyte — and it falls as drives get larger, which means the cheapest way to buy storage is usually to buy fewer, bigger drives. Neither number is printed on the listing in a form you can compare.
The classes
Every drive here sits in one class, assigned from its own specification table and title rather than from the search that surfaced it. Comparisons are made inside a class, because a median across all of them would describe nothing anyone is shopping for.
- NAS drives — Drives rated to run continuously in a multi-bay enclosure, and what that rating actually covers.
- Surveillance drives — Drives tuned for continuous writing from cameras, which is close to the opposite of a desktop workload.
- Enterprise drives — The highest capacities in the corpus, and the lowest price per terabyte in it.
- Desktop drives — The ordinary internal 3.5-inch drive, rated for a working day rather than a working year.
- Laptop drives — 2.5-inch drives, where the form factor caps the capacity and the price per terabyte is the highest here.
- External drives — Drives sold in an enclosure, where the specifications describe the box as much as the drive.
Every class page is still being written, and they are published a couple at a time rather than in one burst.
What a baseline is
A baseline is the median of a specification within one class and one capacity band, with values beyond 1.5× the interquartile range left out of the calculation so a single odd listing cannot move it. Where a group holds fewer than 8 drives, no baseline is published — below that a median describes the sample rather than the market.
What we do not do
We do not test drives. There is no lab here and no benchmark run: everything on this site is derived from what manufacturers publish in their own listings, read consistently across the whole corpus. Where a listing does not state a specification, the page says not stated rather than filling in a plausible default.
We do not publish star ratings or review counts, and we do not print exact prices — a price captured on a scrape date is wrong by the time you read it. The methodology page sets out how the corpus is cleaned and where the process fails, and the about page says who compiles it.
This site earns a commission on qualifying purchases made through its links. That pays for the work and decides nothing about what the figures say — the disclosure sets out exactly what it does and does not mean, and the privacy policy covers what happens when you follow one.
Start with the finder
The hard drive finder narrows the catalogue by class, capacity and budget, and places every result against the median for its own class and band.