They advertise their size. Back in the day, there were programs that let you reformat disks with tweaked parameters -- sectors per track, interleaving, etc -- so you could get a greater capacity. Windows 95 was shipped on a disk formatted for 1680k, for example [1]. Off the shelf disks were hit or miss as far as how big you could reformat them to, with some able to handle close to two megs, and others not able to handle much more than 1.44mb.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Distribution_Media_Format" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Distribution_Media_Format</a>