A mass storage device, such as a removable hard disk, stores data and has an overall storage capacity. The mass storage device includes a panel on which a capacity indicator is positioned, and the capacity indicator displays either a used storage capacity or a free storage capacity of the mass storage device, or displays both free and used storage capacities of the mass storage device. The capacity indicator may be, for example, one or more light emitting diodes (LEDs), or may be an LED or liquid crystal display indicating percentage of the overall storage capacity of the mass storage device that is used, available, or both. A capacity-update program executing on a computer system of which the mass storage device is a part can update the storage capacity information being displayed, or suitable circuitry or a program within the device itself can update such information.