If you need a lot of storage without spending a lot of money, an external hard drive is still the most practical choice. But prices vary wildly between models, and the sticker price alone does not tell you whether you are getting a good deal. A 2TB drive for $59 sounds cheap until you realize a 5TB drive for $89 gives you more than twice the storage per dollar.
That is why price per gigabyte is the single most useful metric when shopping for external storage. It cuts through the marketing and tells you exactly how much storage you get for every dollar you spend.
BuyPerUnit tracks external hard drive prices daily across major retailers and ranks every option by price per GB. Instead of checking dozens of product pages, you can compare them all in one place.
What to Look For in an External Hard Drive
Capacity: The Sweet Spot
Larger drives almost always offer a better price per GB. A 1TB external drive might cost $0.04 per GB, while an 8TB model could come in under $0.02 per GB. For most people, the 4TB to 8TB range hits the best balance between total cost and value per gigabyte.
If you only need a drive for documents and light backups, 2TB is plenty. But if you are storing photos, video, or game libraries, aim for 4TB or higher to get the best bang for your buck.
USB 3.0 vs USB-C
Most modern external hard drives support USB 3.0 speeds at a minimum, which tops out around 5 Gbps. Some newer models use USB-C connectors, which are more convenient but do not necessarily mean faster transfer speeds for a spinning hard drive. The mechanical drive inside is the bottleneck, not the cable.
USB-C is nice for compatibility with newer laptops that lack USB-A ports, but do not pay a premium for it. A USB-A drive with a cheap adapter works just as well.
RPM and Performance
Most portable external hard drives use 5400 RPM platters. Desktop external drives sometimes use 7200 RPM drives, which offer modestly faster read and write speeds. For bulk storage and backups, 5400 RPM is perfectly fine. The difference only matters if you are frequently accessing large files directly from the drive.
Warranty and Reliability
WD, Seagate, and Toshiba all offer two- to three-year warranties on their consumer external drives. Reliability across the major brands is broadly similar for light use. If you are storing anything irreplaceable, the real answer is to keep multiple copies regardless of which brand you choose.
Best Value Picks
Rather than recommending a single model that could be out of stock or repriced by tomorrow, here is what to look for in each tier.
Budget (1-2TB): At this capacity, most major brands price their portable drives within a few dollars of each other. Look for WD Elements, Seagate Expansion, or Toshiba Canvio Basics. Whichever is cheapest per GB on a given day is the best buy.
Mid-Range (4-5TB): This is where the value equation gets interesting. Portable 4TB and 5TB drives routinely dip below $0.02 per GB during sales. The Seagate Portable and WD My Passport lines both compete heavily at this capacity. Check the per-unit price rather than waiting for a specific model to go on sale.
High Capacity (8TB+): At 8TB and above, you are typically looking at desktop drives that need a power adapter. These are bulkier but offer the absolute lowest price per GB. WD My Book and Seagate Expansion Desktop models are the go-to options. Prices fluctuate frequently, so tracking per-GB cost over time helps you spot a real deal versus a fake "sale."
Browse All Hard Drives by Price Per GB →When to Buy an SSD Instead
External SSDs have dropped in price significantly over the past few years, but they still cost three to five times more per gigabyte than traditional hard drives. So when does it make sense to pay the premium?
Choose an SSD if you need:
- Fast access to working files (video editing, photo libraries, running applications)
- Durability for travel (no moving parts means better shock resistance)
- Compact size (most external SSDs are smaller than a credit card)
Stick with an HDD if you need:
- Maximum storage for the lowest price (backups, archives, media libraries)
- Bulk storage above 4TB without breaking the budget
- A drive that will mostly sit on a desk
For the same $100, you could buy a 1TB external SSD or a 5TB external hard drive. If speed is not critical, the hard drive gives you five times the storage. BuyPerUnit lets you compare both categories side by side so you can make the right tradeoff.
If you are unsure, consider buying a large HDD for bulk storage and a small SSD for files you access frequently. That combination gives you the best of both worlds without overspending.
View All Storage Deals →The Bottom Line
External hard drives remain the most cost-effective way to store large amounts of data. The key is to stop comparing sticker prices and start comparing price per gigabyte. A drive that looks expensive at face value might actually be the cheapest option once you account for how much storage you are getting.
Prices change constantly, and the best deal today might not be the best deal next week. That is exactly why we built BuyPerUnit — to track every option and rank them by what actually matters: how much storage you get for every dollar you spend.
Find the Best Price Per GB Right Now →