When buying a laptop, one of the most important decisions you have to make is figuring out how much internal storage you need. Depending on the amount, it can drive up the price of the laptop considerably. For instance, Apple’s latest MacBook Air can be configured with either 256GB or 512GB of internal storage, and if you get the higher-end model that’s going to cost you an extra $200 — that’s a lot. Microsoft’s Surface Laptops, meanwhile, come in 128GB, 256GB, 512GB, and 1TB varieties. How much do you really need? There is no perfect answer, of course. But there are some handy rules of thumb and wrinkles to know about.
The most important thing to know is that the amount of usable storage space a laptop actually has is much less than what is advertised, for two reasons. First, your operating system is taking up space. The latest version of macOS, (High Sierra), for example, takes up a little more than 8GB, while the latest version of Windows 10 takes up about 15GB.
Second, because user-facing specs deal in normal base-10 numbers instead of the less intuitive base-2 numbers computers actually use, hard drives are just always smaller than they are rated to be. According to Lifewire, for each gigabyte that you think your hard drive has, it has about 70.3 megabytes less of disk space.
Using a disk size calculator, and subtracting an extra 20GB for operating system to be on the safe side, you’ll find that “128GB” is more like 99GB, “256GB” is more like 218GB, and “512GB” is more like 456GB.
With that in mind, we generally recommend upgrading to 256GB to give yourself a little breathing room, though 512 is probably overkill for normal use cases.
Some manufactures are already specing out their offerings with that reality in mind. Apple’s new MacBook Air and a 13-inch MacBook Pro, both of which start with a base SSD storage of 256GB (and can be configured upwards), while the previous-generations both started with half that amount. And Apple didn’t increase their prices, either, so you’re essentially buying a new laptop and getting double the storage at no extra charge.
For a better idea of your actual, personal usage, a good place to start is to check how much storage of your current laptop you are using. On a Mac, click on the Apple logo in the top left corner, select “About this Mac” and select “Storage.” On a PC, click the Start button, select “File Explorer” and select “This PC.”
While you might be able to get by on 128GB, it’s probably better to be safe than sorry if you can afford it. It’s generally hard to add space into a laptop, and while you can pick up an external drive to use as backup or even day-to-day storage, it’s going to add bulk to your machine and friction to your workflow.
The reality is that 256GB of internal storage is probably going to be plenty enough for most people who don’t already have (or anticipate having) a ton of locally stored photos, video, video games, or music that can’t either be easily offloaded into the cloud, or to a backup drive. If you don’t immediately feel cramped looking at the number “256,” it’s probably spacious enough for your needs.