Frequently asked questions

It’s a product’s price divided by its capacity in terabytes — the single fairest way to compare two products of different sizes. A larger drive with a scarier sticker is often far cheaper storage per terabyte than a small one. See how we test for the exact calculation.

Usually a high-capacity tier a step or two below the newest flagship, because the fixed cost of a drive’s mechanics is spread across more platters — but the newest, largest drives carry a scarcity premium. The sweet spot moves with the market, so sort the $/TB rankings to see today’s cheapest terabyte.

Because flash memory is simply more expensive to manufacture than spinning platters. Even a budget NVMe or SATA SSD costs many times more per terabyte than a hard drive — that’s the technology, not a bad deal. For bulk capacity, hard drives win; for speed, flash wins. See HDD vs SSD.

Use an SSD (ideally NVMe) for your operating system, applications and active projects, where speed transforms the experience. Use a hard drive for bulk storage, media libraries, backups and archives, where cost per terabyte matters more than speed. Most good setups use both.

Almost always one big drive. Larger drives have a lower cost per terabyte, use fewer bays, cables and watts, and leave room to grow. Buy the largest capacity that still sits near the bottom of the $/TB rankings rather than several small drives that add up to a higher total.

Manufacturers price finished consumer products aggressively and buy drives in volume, so a large external desktop drive can undercut the same-capacity bare internal drive per terabyte. Enthusiasts ‘shuck’ the enclosure to recover the disk inside — cheaper, but it voids the warranty.

Yes, for the right tier. Used enterprise drives often deliver the lowest $/TB anywhere and suit secondary, NAS and archival roles — provided you check SMART health on arrival, confirm the return window, and never keep your only copy on one disk. ‘Recertified’ drives are re-warranted and lower-risk than as-is ‘pulled’ drives. More in this post.

Yes — SAS drives need a SAS host bus adapter (commonly flashed to IT mode); a regular motherboard SATA port won’t connect them. If you’d rather avoid that, choose enterprise SATA drives, which drop into any SATA port. See the enterprise category.

Modern drives are very reliable, but every drive will eventually fail — the only question is when. Failures cluster early (infant mortality) and late (wear-out). The practical response isn’t chasing a ‘perfect’ drive but assuming any drive can die and keeping backups. Our reliability guide covers SMART data and failure patterns.

They differ mainly in write behaviour, not raw reliability. SMR (shingled) drives slow dramatically once their cache fills and can stall RAID rebuilds, so they’re best for write-once archival disks, not arrays. For a NAS or RAID, choose CMR. See CMR vs SMR.

SMART is the self-monitoring data every drive reports — reallocated sectors, pending sectors, power-on hours and more. Always check it on a new used drive immediately, and periodically on drives in service. Rising reallocated or pending sector counts are early warning signs. The reliability guide explains which attributes matter.

RAID protects against drive failure and keeps a system online — it does nothing against accidental deletion, ransomware, fire, theft or a controller fault. RAID is not a backup. You still need separate, ideally off-site copies. See RAID explained and the backup guide.

Keep at least 3 copies of your data, on 2 different types of media, with 1 copy off-site. It survives a single drive failure, a device-wide disaster and most local catastrophes. Our data backup strategy guide shows how to build one affordably.

For bulk cold backups, a second set of large hard drives or LTO tape gives the lowest cost per terabyte; tape wins at archive scale and draws zero standby power. For an immutable, air-gapped copy of important files, archival Blu-ray is worth considering. Match the medium to how often you’ll read the data back.

Hard drives can sit unpowered for years but aren’t designed for indefinite cold storage; flash (SSDs, cards) can lose charge if left fully unpowered for very long periods. For true long-term archival, LTO tape (rated up to ~30 years stored correctly) and archival optical media are the dependable choices. Power working drives on periodically.

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No. The order is always lowest cost per terabyte first, layered with editorial judgement about fitness for purpose — never by what a retailer pays. A drive that earns us nothing outranks one that does if it’s cheaper per terabyte. See how we test.

Daily. Prices and the resulting rankings reflect the latest tracked figures each time a page loads, so the cheapest product in a category can change between visits. Always confirm the live price at the retailer before buying.

More than 3,200 products across 11 categories — internal and external hard drives, SATA and NVMe SSDs, external SSDs, enterprise/SAS, LTO tape, optical, memory cards, USB flash and RAM. Browse them all on the $/TB rankings or by category.

Please tell us — accurate data is the whole point of the site, so corrections jump the queue. Email [email protected] with the product and the discrepancy, or use the contact page.