How data storage units work
Computers store information in bits — single 0s and 1s. Eight bits make one byte, the basic unit of storage. Larger amounts are grouped into kilobytes, megabytes, gigabytes, terabytes and petabytes. The catch is that there are two ways to scale up, and they give different numbers.
In the decimal (SI) system each step multiplies by 1000: 1 KB = 1000 bytes, 1 MB = 1000 KB, 1 GB = 1000 MB, and so on. In the binary (IEC) system each step multiplies by 1024, using distinct names — kibibyte (KiB), mebibyte (MiB), gibibyte (GiB), tebibyte (TiB). The IEC names exist precisely to remove the ambiguity, because KB, MB and GB have historically been used loosely for both.
Reference note: this tool computes exactly for the selected base. Very large or fractional inputs are shown using high-precision number handling, so converting MB to GB or TB to GB stays accurate.
Frequently asked questions
- How many MB are in a GB?
- In decimal (SI) units there are 1000 MB in 1 GB. In binary (IEC) units there are 1024 MiB in 1 GiB. Storage marketing uses the decimal figure; operating systems often report the binary one.
- What is the difference between KB and KiB (1000 vs 1024)?
- A kilobyte (KB) is 1000 bytes in decimal SI units; a kibibyte (KiB) is 1024 bytes in binary IEC units. The KiB / MiB / GiB names were introduced to remove the long-standing 1000-vs-1024 ambiguity.
- How many bytes are in a KB?
- A decimal kilobyte (KB) is 1000 bytes, while a binary kibibyte (KiB) is 1024 bytes. Use the 1000 / 1024 base toggle to switch between the two.
- What is the difference between bits and bytes?
- A byte is 8 bits. Bits (lower-case b) are used for transfer rates like Mbps; bytes (upper-case B) for storage like MB. So a 100 Mbps connection is about 12.5 MB/s.
- Why does my drive show less space than advertised?
- Makers advertise in decimal units (1 TB = 1,000,000,000,000 bytes) but many operating systems count in binary, so the same drive reads as about 931 GiB. No space is missing — it is just two ways of counting.
- What is a terabyte (TB)?
- A terabyte is 1000 gigabytes, or 1,000,000,000,000 bytes, in decimal units. A tebibyte (TiB) is 1024 gibibytes, or 1,099,511,627,776 bytes.