Convert GB to MB in binary (×1,024) or decimal (×1,000). Includes the difference table and why your 1 TB drive shows only 931 GB in Windows.
Binary multiplies by 1,024 because computers address memory in powers of two (2^10 = 1,024). The official binary names are GiB and MiB; decimal GB/MB (×1,000) is what drive makers print on the box.
| GB | MiB (binary ×1,024) | MB (decimal ×1,000) | Difference |
|---|---|---|---|
| 1 | 1,024 | 1,000 | 24 MB (2.4%) |
| 2 | 2,048 | 2,000 | 48 MB |
| 4 | 4,096 | 4,000 | 96 MB |
| 8 | 8,192 | 8,000 | 192 MB |
| 16 | 16,384 | 16,000 | 384 MB |
| 32 | 32,768 | 32,000 | 768 MB |
| 64 | 65,536 | 64,000 | 1,536 MB |
| 128 | 131,072 | 128,000 | 3,072 MB |
| 256 | 262,144 | 256,000 | 6,144 MB |
| 512 | 524,288 | 512,000 | 12,288 MB |
| 1,024 | 1,048,576 | 1,024,000 | 24,576 MB |
Why a 1 TB drive shows 931 GB: the label uses decimal (1,000,000,000,000 bytes) but Windows reports in binary, 10^12 ÷ 1,024³ ≈ 931 GiB. Nothing is missing.
Both, depending on the system. Storage manufacturers use decimal: 1 GB = 1,000 MB. Computer memory and Windows use binary: 1 GiB = 1,024 MiB. The binary units officially have their own names (GiB, MiB, KiB) since 1998, but everyday writing says GB for both.
Computers work in powers of two, and 2^10 = 1,024, the closest power of two to 1,000. Every binary step (KiB, MiB, GiB, TiB) multiplies by 1,024 instead of 1,000, so the gap grows: 2.4% at MB, 5% at GB, 7.4% at TB, 10% at PB.
The label is decimal and your operating system reports binary. A 1 TB drive holds 10^12 bytes; Windows divides by 1,024³ and shows 931 GiB. You are not being short-changed, it is the same bytes counted in different units.
For buying storage and measuring download sizes, decimal (×1,000) matches the packaging. For RAM, operating-system figures and technical specs, binary (×1,024) matches what the machine reports.