MB to Bytes Converter

How many bytes are in a megabyte?

It depends on the convention, and this converter lets you choose. By default it uses the binary count that operating systems and memory specifications have long relied on: 1 MB = 1,024 × 1,024 = 1,048,576 bytes. Tick Use SI standard and it switches to the decimal definition, where mega means exactly one million: 1 MB = 1,000,000 bytes.

binary: bytes = MB × 1,048,576

SI: bytes = MB × 1,000,000

The two answers differ by 48,576 bytes per megabyte, roughly 4.9%. That is negligible for one small file and noticeable for large ones: a 700 MB disc image is 734,003,200 bytes in binary counting but 700,000,000 bytes in SI counting.

Difference between MB and bytes

A byte is the basic unit of digital storage: eight bits, enough for one character of plain English text. A megabyte is a large multiple of the byte, so going from MB to bytes is always a multiplication and the number gets about a million times bigger.

Both conventions share the symbol MB, which is why one file can show two different sizes in two programs. Windows has long reported sizes in binary multiples while still printing KB, MB and GB, whereas macOS (since version 10.6) and most drive makers use decimal ones. The IEC suggested a way out in the late 1990s: a binary megabyte is a mebibyte (MiB) of 1,048,576 bytes, and MB is kept for 1,000,000 bytes. Everyday software rarely follows that naming, so the tool offers both counts.

How to convert MB to bytes

1. Decide which convention you need: binary (the default) or SI.
2. Multiply the number of megabytes by 1,048,576 for binary, or by 1,000,000 for SI.
3. Read the result in bytes.

The result is shown as a plain number without thousands separators, so it can be pasted straight into a spreadsheet or a script. It is rounded to four decimal places.

MB to bytes conversion table

Common mistakes

• Mixing conventions in one calculation. Choose binary or SI and stay with it, otherwise totals will not add up.
• Confusing bytes with bits. A capital B is a byte and a lowercase b is a bit. To count megabits instead, use the MB to Mbit converter.
• Expecting a storage label to match what the system reports. A card sold as 256 MB holds 256,000,000 bytes, which a system counting in binary shows as 256,000,000 ÷ 1,048,576 ≈ 244.14 MB.

For the reverse direction use the bytes to MB converter. To step up or down one unit, see the MB to KB converter and the MB to GB converter, or compare more units at once with the data storage converter.