Two different ways to count a gigabyte
Drive makers count storage in decimal units: one gigabyte is 1 billion bytes. So a marketed 500GB drive contains about 500 billion bytes.
Windows traditionally calculates capacity using binary units, where each step is based on powers of 1,024. A binary gibibyte (GiB) is 1,073,741,824 bytes—about 7.4% larger than a decimal gigabyte. Divide the drive’s roughly 500 billion bytes by that larger unit and the result is about 466 GiB. Windows may label that figure “GB,” even though its calculation is binary.
The space is counted differently, not taken away
The apparent drop is mostly a unit mismatch, not evidence that the drive has lost roughly 35GB. The same number of bytes is being expressed in larger units. Other operating systems may show a number closer to 500 because they use decimal units, or they may label binary units as GiB.
The formatted volume can be a little smaller still. Formatting creates a file system—the structure the computer uses to organize files—and some space may be reserved for its bookkeeping or other partitions. That reduction is separate from the decimal-versus-binary conversion.
In practical terms, a new 500GB drive showing roughly 465 “GB” on a Windows PC is behaving as expected: the label says one thing, while the computer is counting with a different-sized unit.
