Quick answer: KB vs KiB, MB vs MiB, GB vs GiB
Storage units use two different systems:
- Decimal SI units use powers of 1000:
1 KB = 1,000 bytes,1 MB = 1,000,000 bytes,1 GB = 1,000,000,000 bytes. - Binary IEC units use powers of 1024:
1 KiB = 1,024 bytes,1 MiB = 1,048,576 bytes,1 GiB = 1,073,741,824 bytes.
That is why a drive sold as 1 TB can appear as about 931 GiB in an operating system:
1,000,000,000,000 bytes / 1,073,741,824 bytes per GiB = 931.32 GiBUse this Storage Unit Converter when you need to translate between marketing storage sizes, operating system file sizes, memory units, network transfer calculations, and binary engineering notation.
How to use the Storage Unit Converter
- Enter a numeric value in the input field.
- Select the source unit from the dropdown (SI decimal or IEC binary).
- Read the equivalent values in bytes, KB, MB, GB, TB, KiB, MiB, GiB and TiB.
- Use the decimal column for disk labels, SSD packaging and bandwidth estimates; use the binary column for RAM, file systems and operating system capacity displays.
Standards explained
There are two competing standards for storage unit prefixes.
SI (decimal, base-10)
Defined by the International System of Units. Each prefix multiplies by 1,000:
| Unit | Symbol | Bytes |
|---|---|---|
| Kilobyte | KB | 1,000 |
| Megabyte | MB | 1,000,000 |
| Gigabyte | GB | 1,000,000,000 |
| Terabyte | TB | 1,000,000,000,000 |
| Petabyte | PB | 1,000,000,000,000,000 |
Used by hard drive manufacturers, network bandwidth specs, and the SI standard.
IEC (binary, base-2)
Defined by IEC 80000-13. Each prefix multiplies by 1,024:
| Unit | Symbol | Bytes |
|---|---|---|
| Kibibyte | KiB | 1,024 |
| Mebibyte | MiB | 1,048,576 |
| Gibibyte | GiB | 1,073,741,824 |
| Tebibyte | TiB | 1,099,511,627,776 |
| Pebibyte | PiB | 1,125,899,906,842,624 |
Used by operating systems (Linux, macOS), RAM specifications, and file system tools.
Common conversions
| Input | Decimal result | Binary result |
|---|---|---|
| 1 KB | 1,000 bytes | 0.9766 KiB |
| 1 KiB | 1,024 bytes | 1.024 KB |
| 1 MB | 1,000,000 bytes | 0.9537 MiB |
| 1 MiB | 1,048,576 bytes | 1.0486 MB |
| 1 GB | 1,000,000,000 bytes | 0.9313 GiB |
| 1 GiB | 1,073,741,824 bytes | 1.0737 GB |
| 1 TB | 1,000,000,000,000 bytes | 931.32 GiB |
Which unit should I use?
Use KB, MB, GB and TB for storage products, internet speed discussions, cloud storage quotas and most consumer-facing documentation. These are decimal units and match the way manufacturers usually label drives.
Use KiB, MiB, GiB and TiB when exact binary capacity matters: memory pages, RAM sizes, file system blocks, low-level storage tooling, operating system reports and programming tasks.
If you are comparing a drive label with what Windows, macOS or Linux shows, convert the labeled decimal capacity into GiB or TiB. The device has not necessarily lost space; the two displays may simply be using different unit systems.
Storage unit formulas
Decimal conversion:
bytes = value × 1000^unit_powerBinary conversion:
bytes = value × 1024^unit_powerFor example, converting 256 GB to GiB:
256 GB = 256 × 1,000,000,000 bytes
256,000,000,000 / 1,073,741,824 = 238.42 GiB