Every console fills up. A few modern games eat more than 100 GB each, and the store page never mentions that the first thing to do after unboxing is plan the storage. The market then offers a dozen plausible answers — internal NVMe sticks, portable SSDs, microSD cards, proprietary expansion cards — and only some of them work on any given machine. The difference is not quality; it is that each console gates which storage is allowed to run games, and the gate is in a different place on each machine.
So the real question is never "will it fit." Files almost always fit somewhere. The two questions that decide your money are: what can hold the files, and what can run the game from that place. A drive that can hold everything but run nothing is a very expensive archive shelf.
PlayStation 5: one fast lane inside, a shelf outside
Sony's official requirements for the internal M.2 SSD slot are specific, and buyers trip over all three of them at some point. The drive must be a PCIe Gen4 x4 NVMe SSD in the correct socket form; Sony recommends sequential read of 5,500 MB/s or faster; and a heatsink is required, with the whole assembly fitting strict thickness and width limits inside the expansion bay. Capacity runs from 250 GB up to a maximum of 8 TB on current system software. None of this is exotic — Gen4 drives with heatsinks are a standard retail category now — but a drive bought "because it's fast" without checking the size limits with its heatsink attached is the classic PS5 upgrade mistake: it's the fit, not the speed, that sends people back to the store.
The second half of the PS5 story is the external USB drive, and its rule is simple: PS5 games can be stored on an external USB drive, but they can only be played from the internal SSD. An external drive works as an archive — move a finished game out, pull it back in when you want it — and this saves real time compared with redownloading. PS4 games, by contrast, run directly from extended USB storage, which makes a cheap external drive the natural home for a large PS4 library. Saved data from PS4 games can also be copied to a USB drive as a backup; PS5 save data rides the console and cloud saves instead.
Xbox Series X|S: the card is the fast lane
Microsoft's support page states the rule in one sentence: to play games that are optimized for Xbox Series X|S, they need to be installed on the console's internal SSD or a Storage Expansion Card. The expansion card is a proprietary format that plugs into a dedicated port on the back and matches the internal drive's performance, so a Series-optimized game plays straight off it. That guaranteed speed is why the card costs more per terabyte than generic drives — you are paying for the absence of the archive step.
The USB external drive has exactly the opposite split from the PS5's. It can store — archive — Series-optimized games, but it cannot run them; launching one means moving it to internal storage or the card first. What it can run directly is the older library: Xbox One, Xbox 360, and original Xbox titles play straight from a USB drive. If your collection skews to those generations, a plain external HDD is the cheapest useful upgrade you can buy; if it skews to Series games, the expansion card is the only thing that adds playable capacity.
Nintendo Switch: the console where the card is the library
The Switch family inverts the PS5 and Xbox model. On the original Switch, a microSD card (UHS-I, up to 2 TB) holds downloaded games and screenshots, and games run from it happily — the card is not an archive, it is the main library. The one thing it never holds is save data: game saves live in the console's internal storage, which is why the card is not a backup and why a lost console takes its saves with it unless you've used the cloud backup option.
The Switch 2 keeps the model and changes the medium: the Switch 2 is only compatible with microSD Express cards. The microSD card that served your original Switch is not accepted — Nintendo's own support page is blunt about it, and so is the price tag, because Express cards cost noticeably more than the UHS-I cards everyone already owns. This is the single most surprising trap of the three consoles: the card in your drawer, perfect for the old Switch, is dead weight in the new one. When buying, the label to look for is literally "microSD Express" — not a speed class, not a brand claim.
The Rules That Hold Everywhere
Buy to the console's spec sheet, not the PC one. A PC builder's instinct — fastest drive for the money — fails on consoles, where the questions are interface generation, physical fit, and proprietary format. The official requirements page for your exact console is the product specification; marketplace listings are advertising.
Capacity is the easy part. Any of these paths gets you more gigabytes. The differentiator is the "runs from" gate: which of your games are allowed to execute from that drive. A full archive shelf and an empty fast lane is the most common outcome of buying by price per terabyte alone.
Saves are a separate problem. On Switch they stay on internal storage; on PS5, PS4-era saves need manual backup to USB; on Xbox they ride the profile. Whichever machine you own, the storage expansion plan and the save backup plan are two different plans.
The premium on proprietary cards is the price of the fast lane. Expansion cards and Express cards cost more per terabyte because they guarantee execution speed instead of just holding files. Decide whether you are buying a library (run things) or a shelf (hold things) before comparing prices.
Before You Buy
- Count what's actually full: is it Series-era or PS5-era games, or the older library? The generation you need offloaded decides which storage type helps.
- Open the official requirements page for your console model — capacity, speed, dimensions, format — and buy to it, not to a listing's compatibility badge.
- For the PS5, check the drive-with-heatsink dimensions, not the bare drive's.
- For the Switch 2, confirm the card says microSD Express.
- Plan the split deliberately: fast lane for the games you're playing now, archive shelf for the ones you'll come back to. Moves and downloads are one-directional chores; pick the arrangement that minimizes how often you do them.
Storage expansion is one of the few console purchases where the trap is fully documented in advance. The rules are public, per console, and short — the fifteen minutes reading them is the cheapest part of the upgrade.