Buying a computer SSD sounds simple until you see 2.5-inch, M.2, SATA, NVMe, PCIe Gen3, Gen4 and Gen5 on the same page. This guide breaks it into the four questions that decide what you buy.

What form factor does your device take?

2.5-inch SATA: common in older laptops and desktops. It looks like a thin hard drive.

M.2 2280: a small stick that plugs into the board. The number means 22mm wide and 80mm long.

Portable (external): a USB drive for backup and carrying large files.

SATA or NVMe? An M.2 slot can be SATA-based or NVMe-based, and some slots only support one. Check your motherboard or laptop manual.

SATA: up to about 550MB/s

NVMe PCIe Gen3: about 3,500MB/s

NVMe PCIe Gen4: about 7,000MB/s

NVMe PCIe Gen5: 10,000MB/s class

How much capacity?

256GB: basic use

512GB: the comfortable starting point for most laptops

1TB: for large libraries, games and projects

2TB and up: for editing and heavy workloads

Which brand and warranty?…