Real Storage Capacity Calculator
Real Storage Capacity Calculator – an easy-to-use tool that helps you find out the actual usable space of your hard drive, SSD, or USB flash drive. Manufacturers label storage in decimal units (GB = 1,000,000,000 bytes), while operating systems like Windows and macOS display space in binary units (GiB = 1,073,741,824 bytes).
This calculator instantly converts advertised capacity into real usable capacity, so you can understand how much data your device can truly hold.
FAQs
Why does my 1 TB hard drive show less than 1 TB in Windows?
Manufacturers use decimal units (1 TB = 1,000,000,000,000 bytes), but Windows reports binary units (1 TiB = 1,099,511,627,776 bytes). That’s why a 1 TB drive appears as ~931 GiB.
How do I calculate the real usable storage of a disk?
Enter the advertised size (in GB or TB) into the calculator. It converts decimal units to binary units so you see the actual space your OS will display.
What is the difference between GB and GiB?
GB (Gigabyte) – 1,000,000,000 bytes, used by manufacturers.
GiB (Gibibyte) – 1,073,741,824 bytes, used by operating systems.
Does formatting affect usable storage?
Yes. File system structures, reserved system space, and formatting overhead reduce the usable capacity slightly. The calculator shows the OS-recognized size before formatting overhead.
Why does a 32 GB USB drive show about 29.8 GB?
A 32 GB drive (decimal) equals ~29.8 GiB in binary units. Windows reports the binary size, which is smaller than the manufacturer’s advertised decimal size.
Why do storage manufacturers use decimal units?
Decimal units (GB = 10⁹ bytes) are simpler for marketing and advertising. Binary units are more precise for computers, which use base-2 architecture.
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