Disclosure: This is an affiliate marketing website for Amazon. If you make a purchase through links on this site, I may earn a small commission at no extra cost to you. This helps fund and maintain this website. Thanks!
Written by Lucky, who has spent over a decade running home-lab NAS builds and still sources every drive by price per TB before buying.
How to Compare HDD, SSD and External Hard Disk Prices by Cost per TB
Disk Prices helps you compare drives easily: divide the price by capacity in terabytes to get a single $/TB figure, then line that number up across different conditions and technologies — internal or external hard disk, SSD, or RAM. A $60 external hard disk with 4TB works out to $15/TB, whereas a $180 internal SSD with 2TB comes to $90/TB. Once everything is expressed the same way, external hard disks, internal hard drives, SSDs, and used enterprise drives all become directly comparable-no guesswork.
That single idea – price per TB – is the backbone of every filter below. Here’s how each one changes what you’re actually comparing.
What Does “Price per TB” (or Price per GB) Actually Mean?
Price per TB is simply the listed price divided by the drive’s rated capacity. It’s the only fair way to compare a 500GB SSD against an 18TB hard drive, because raw price alone tells you nothing about how much storage you’re getting for it.
Smaller devices — memory cards, flash drives, small SSDs — are usually easier to read in price per GB instead, since the per-TB number gets awkward at that scale. Switching between the two units doesn’t change the math, only the decimal point.
New vs. Used: What Actually Changes When You Filter by Condition
New drives carry a full manufacturer warranty and zero power-on hours. You’re paying for that certainty, and it shows up directly in a higher price per TB.
Used and refurbished drives have already logged hours in another system. That’s not automatically a problem — enterprise drives are often pulled from data centers well before they wear out — but it does mean the warranty is shorter or gone, and the price per TB should reflect that lower certainty.
A good rule of thumb: the gap in price per TB between a new and a used listing of the same drive is a rough proxy for how much risk you’re being asked to absorb. A small gap on a drive with a long remaining warranty is a very different trade-off than a large gap on a bare-drive, no-warranty listing.
Rotational (HDD) vs. Solid State (SSD): Picking the Right Technology
Rotational drives (HDDs) still hold the lowest price per TB of any spinning or solid-state format, which is why they remain the default for bulk storage, backups, and archives where raw capacity matters more than speed.
Solid state drives (SSDs) cost more per TB but read and write data with no moving parts, so they win for anything latency-sensitive: boot drives, active project files, databases, or a laptop that needs to survive being dropped in a bag.
Independent, large-scale reliability data — for example Backblaze’s ongoing hard drive failure-rate reports — is worth a look if you’re deciding how much to trust a used mechanical drive versus paying up for solid state.
Many buyers split the difference: an SSD for the operating system and active files, paired with a higher-capacity HDD for everything else. Filtering by both types side by side, sorted by price per TB, makes that split easy to price out.
Internal vs. External Hard Disk: 3.5″ vs. 2.5″ Drives
Internal 3.5″ drives are the standard for desktops and NAS units — the largest capacities and the lowest price per TB in the entire catalog.
Internal 2.5″ drives fit laptops and small-form-factor builds, trading some capacity headroom for a smaller footprint.
External 3.5″ and External 2.5″ are the same drive mechanisms housed in an enclosure with a USB interface, aimed at anyone who wants storage without opening a case. Expect a modest premium over the equivalent bare internal drive for the enclosure and cable.
Internal Hybrid (SSHD) drives pair a small flash cache with a mechanical platter, aiming for HDD-like capacity with some SSD-like responsiveness for frequently accessed files. It’s a middle ground, and the price per TB usually reflects that.
Internal SAS drives are built for servers and storage arrays — dual-port connections, higher duty cycles, and pricing aimed at business buyers rather than a typical desktop upgrade.
SSD Form Factors Explained: SATA, NVMe, M.2, and U.2/U.3
External SSD vs. Internal SSD — the difference is the enclosure and interface, not the underlying flash. An internal SSD installs directly on a motherboard or in a drive bay; an external SSD connects over USB or Thunderbolt for portable use.
M.2 SATA drives use the compact M.2 connector but still run over the older SATA protocol, so speeds are capped similarly to a 2.5″ SATA SSD — a budget-minded way to get a small-form-factor drive.
M.2 NVMe drives use the same connector but talk directly over PCIe, which is where the real speed jump happens. This is the standard choice for a modern laptop or desktop boot drive.
U.2/U.3 drives look like a 2.5″ bay drive but carry an NVMe connection built for servers — hot-swappable, higher endurance, and priced accordingly for datacenter and workstation use.
Memory (RAM) Filters: DDR5 vs. DDR4, UDIMM vs. SODIMM vs. RDIMM
DDR5 vs. DDR4 describes the memory generation — DDR5 is newer, faster, and typically carries a higher price per GB than the now-mature DDR4 market.
UDIMM is the standard unbuffered module used in most desktops. SODIMM is the compact version built for laptops and small-form-factor PCs. RDIMM adds a register buffer between the memory and the controller, which is what allows servers and workstations to run large numbers of high-capacity modules reliably.
The short version: match the DIMM type to the system it’s going into first, then compare price per GB within that type — mixing DDR generations or DIMM types isn’t a pricing decision, it’s a compatibility one.
Removable and Flash Storage: microSD, SD, Compact Flash, CFast, CFexpress, and USB Flash
microSD and SD cards cover phones, cameras, and handheld devices, with SD generally holding a capacity and speed edge over its smaller sibling.
Compact Flash (CF) and CFast are older professional camera and industrial formats, still in active use in equipment that was built around them.
CFexpress is the current high-speed standard for professional video and photography, sitting well above CF and CFast in both throughput and price per GB.
USB Flash drives remain the simplest way to move files between systems, with price per GB scaling down sharply as capacity goes up.
Optical discs are a small slice of the market now, but they still serve two groups well: long-term archival storage that doesn’t depend on a spinning motor or flash cell holding a charge, and software/media authoring workflows built around disc formats.
BD-R and DVD-R / CD-R are write-once — ideal for a permanent archive copy. BD-RE, DVD-RW, and CD-RW are rewritable, better suited to backups you’ll overwrite repeatedly. Blu-ray (BD) formats hold far more data per disc than DVD or CD, which is where most of the price-per-GB difference between them comes from.
LTO Tape: LTO-3 Through LTO-9 for Backup and Archive
LTO tape is built for one job: storing large volumes of data offline, at a very low cost per TB, for long-term retention. Each generation roughly doubles the native capacity of the one before it, while staying read-compatible with the previous generation and write-compatible one generation back.
That backward compatibility matters when filtering by generation — a business standardized on LTO-7 drives can usually still read LTO-6 tapes, so the generation filter is really a question of which drive hardware you already own.
For the exact native and compressed capacity of each generation, the LTO Ultrium consortium’s official roadmap is the source most IT teams cite when planning a tape refresh.
Because tape holds the lowest price per TB of any format in this catalog by a wide margin, it remains the default for compliance archives, disaster-recovery copies, and any dataset that needs to sit untouched for years.
How to Use the Capacity and Price Filters to Narrow Results
Setting a Minimum and Maximum capacity range first — before sorting by price per TB — keeps the comparison honest. Sorting an unfiltered list by price per TB alone tends to surface the smallest drives on the market, since tiny capacities often carry the lowest per-unit cost even though they’re not what most buyers are actually shopping for.
Once a realistic capacity range is set, switching the price unit between per TB and per GB is mostly about readability: per TB reads more naturally for anything above roughly 500GB, per GB for anything below it.
A hard disk drive is a data storage device that reads and writes information magnetically on spinning platters. It’s the traditional storage technology in most desktops, laptops, and servers — cheaper per TB than an SSD, but slower and more sensitive to physical shock.
What do hard disks do?
They store your operating system, programs, and files persistently, keeping the data even when the computer is powered off. Every time you save a file, open an application, or boot your computer, the hard disk is what’s being read from or written to.
What is price per TB and why does it matter?
It’s the listed price divided by the drive’s capacity in terabytes. It matters because it’s the only number that lets you compare a small SSD, a large HDD, and a used enterprise drive on equal footing instead of comparing sticker prices for very different amounts of storage.
What is the best external hard disk by price per TB right now?
Prices shift daily on Amazon, so there’s no single fixed answer — filter the table above to “External” under either Rotational (HDD) or Solid State (SSD), then sort by price per TB to see the current cheapest option. Large-capacity external HDDs usually win on raw $/TB, while external SSDs cost more per TB but add speed and durability.
Is a used hard drive safe to buy?
It depends on remaining warranty and how the drive was used. A used drive from a controlled server environment with a warranty still attached carries a very different risk profile than a bare, unwarranted drive of unknown history — reliability data from independent testers is a useful reference point either way.
How do I erase or wipe a hard disk drive?
Deleting files or formatting a drive doesn’t fully remove the data — a proper wipe overwrites the entire disk with a dedicated tool (like a manufacturer’s secure-erase utility or shred/diskpart commands) so it can’t be recovered. This matters most before selling or disposing of a used drive, which ties back to buying used drives safely above.
What’s the difference between SATA and NVMe SSDs?
SATA SSDs use the older, slower storage interface originally built for hard drives. NVMe SSDs connect over PCIe, giving them significantly higher throughput — most current laptops and desktops are built around NVMe as the primary drive.
Can I use an internal SSD as external storage?
Yes, with a compatible external enclosure that matches the drive’s interface (SATA or NVMe). This is often a lower price per TB than buying a pre-built external SSD, at the cost of assembling it yourself.
What is the difference between M.2 and U.2/U.3 drives?
M.2 is a compact card-style connector used in laptops and desktops. U.2/U.3 uses a 2.5″ form factor with an NVMe connection built for hot-swap server and workstation bays — same underlying NVMe protocol, different physical format and target use case.
Is DDR5 RAM compatible with DDR4 motherboards?
No. DDR5 and DDR4 use different physical connectors and are not interchangeable — the memory type has to match what the motherboard was built to support.
What is LTO tape used for today?
Long-term backup and archival storage where a very low price per TB matters more than fast random access — compliance archives, disaster-recovery copies, and cold datasets are the most common uses.
What is the difference between BD-R and BD-RE?
BD-R is write-once, making it a good fit for a permanent archive copy. BD-RE is rewritable, better suited to a backup disc you plan to overwrite on a regular schedule.
About the Author
Lucky is the solo developer behind diskprices.store, built out of a decade-plus habit of tracking hard drive and SSD prices for personal home-lab and NAS builds. Every filter on this page — condition, form factor, price per TB — reflects a real buying decision Lucky has had to make while sourcing drives for their own server rack.
Important Affiliate & Pricing Disclosure
This site participates in the Amazon Associates Program and earns a commission on qualifying purchases at no extra cost to you. Prices and availability shown are snapshots and may differ from Amazon’s current listing.
