Don't be fooled by the advertised 32GB of storage in Microsoft's Surface with Windows RT tablet. The actual amount of available storage in the $500 model is closer to 16GB. See Microsoft Surface RT review.
A new FAQ from Microsoft lays out exactly how much usable storage is available in this version of the Surface and where the unusable storage has gone. The Windows RT operating system, the preview version of Microsoft Office, and other built-in apps take up about 8GB of storage. Another 5GB are reserved for Windows recovery tools.
What about the last 3GB of unavailable storage? It's not exactly gone, but Windows' File Explorer calculates capacity using the binary system, in which 1GB equals 1,073,741,824 bytes. Advertised capacity uses the decimal system, in which 1GB equals 1 billion bytes. The difference in formatting means a lower number of gigabytes as reported in File Explorer.
In the 64GB Surface, the same amount of storage is unavailable for use, bringing the actual formatted capacity down to 46GB.
How do other tablets measure up?
In fairness, practically every computing device on the market advertises more storage than what's actually available, due to the same combination of operating system requirements, preloaded software and differences in calculation.
Even so, the difference in advertised versus actual storage in the Surface with Windows RT is greater than what's typical for a tablet. Apple's 32GB iPad, for instance, comes with roughly 28GB of available storage out of the box, and the 16GB Nexus 7 has a little more than 13GB available to users.
Surface users can eke out a little more storage by uninstalling some of the Modern-style apps that come with the tablet. The Surface also includes a MicroSD card slot for up to 64GB more storage, as well as a USB port that supports external hard drives and flash drives.
Microsoft's SkyDrive service is also integrated with the operating system, and it provides 7GB of online storage for free. But none of those options can be used to install more apps. For that, you'll need a Surface with greater storage capacity.
Be angry at Microsoft if you want, but the reality is that every company gets away with over-advertising storage to some degree. Microsoft deserves some credit for explaining actual storage capacity in a clear way, but it would be much easier for consumers if companies made these numbers clear to all buyers, instead of burying the facts in the fine print or on a separate FAQ page.