Data Units Converter

Storage and memory units

The smallest unit of digital information is the bit, a single 0 or 1. Eight bits make one byte, the unit used for files, memory and disks. Larger amounts are written with the usual prefixes, and each prefix has two meanings: a decimal one used by the International System of Units (SI) and a binary one that grew out of how computer memory is addressed.

The converter counts in 1,024s by default, which matches how many operating systems report file and memory sizes. Tick Use SI standard to count in 1,000s, which is how drive manufacturers, most cloud providers and network equipment describe capacity.

Bandwidth and transfer-rate units

A transfer rate is an amount of data per second. Connection speeds are quoted in bits per second: bps, kbps, Mbps, Gbps and Tbps, each step being a factor of 1,000 in SI counting. File-transfer figures in software are usually in bytes per second: B/s, KB/s, MB/s, GB/s and TB/s.

The two families differ by a factor of eight, so the same link is described by very different-looking numbers. A line sold as 100 Mbps moves 100 million bits per second, which is 12.5 million bytes per second.

Network speeds are defined with decimal prefixes, so tick Use SI standard when you step between prefixes on a link, for example Gbps to Mbps (1,000) or Gbps to MB/s (125). Bits and bytes use the same prefix step, so the factor of eight between Mbps and MB/s holds either way: 8 Mbps is exactly 1 MB/s with the box ticked or not. Without the tick, each step is 1,024, so 1 Gbps is 1,024 Mbps and 128 MB/s.

How to convert between data units

1. Enter the amount in the first box and choose its unit.
2. Choose the unit you want in the second drop-down. The answer updates immediately and is rounded to four decimal places.
3. Decide whether to tick the SI box. Leave it empty for 1,024-based sizes, tick it for 1,000-based sizes and for network speeds. The choice applies to bit units and byte units alike.

target = amount × (bytes in source unit) ÷ (bytes in target unit)Bits count as one eighth of a byte, and every prefix step is 1,000 (SI) or 1,024 (box left empty), for bit units and byte units alike.

Amounts and rates cannot be converted into each other, because one is a quantity and the other a quantity per second. If you pick one of each, the answer box reads "switch to compatible output". To find how long a transfer takes you need both, which is what the download time calculator does.

Conversion examples

KB to MB. A 2,560 KB image is 2,560 ÷ 1,024 = 2.5 MB in binary units, or 2,560 ÷ 1,000 = 2.56 MB in decimal units. See also the KB to MB converter.

GB to MB. A 3.5 GB download is 3.5 × 1,024 = 3,584 MB binary, or 3.5 × 1,000 = 3,500 MB decimal. The GB to MB converter shows the same thing for a single pair of units.

Mbps to MB/s. 100 Mbps ÷ 8 = 12.5 MB/s, with the SI box ticked or not. Real transfers run below this ceiling because of protocol overhead and server limits. The Mbps to MB/s converter is a shortcut for this pair.

Mbit to MB. A 100 Mbit file holds 100 ÷ 8 = 12.5 MB under either setting. Lowercase "bit" and uppercase "B" matter here; the Mbit to MB converter isolates this step.

Putting a speed and a size together. A 4 GB file on a 200 Mbps line is 4 × 8 × 1,000 = 32,000 Mbit, and 32,000 ÷ 200 = 160 seconds, which is 2 minutes 40 seconds at the full line rate.

Connection speed reference (SI)

Common mistakes

• Confusing b and B. A lowercase b is a bit and an uppercase B is a byte. Mbps and MB/s differ by a factor of eight.
• Using 1,024 for network speeds. Line rates are decimal, so a gigabit link is 1,000,000,000 bits per second.
• Expecting a labelled size to match what the system reports. A drive sold in decimal units shows a smaller number in a system that counts in binary units; the difference is the unit, not missing space. The TB to GB converter walks through an example.