How many bytes are in a megabyte?

It depends on which system you use. In the binary system used by operating systems and RAM specifications, 1 megabyte (MB) equals 1,048,576 bytes (1024 x 1024). In the decimal system used by storage manufacturers and network speeds, 1 megabyte equals exactly 1,000,000 bytes (1000 x 1000). This is why a 500 GB hard drive shows as slightly less in Windows or macOS: the OS uses binary (1 GiB = 1,073,741,824 bytes) while the manufacturer uses decimal (1 GB = 1,000,000,000 bytes).

What is the difference between MB and MiB?

MB (megabyte) and MiB (mebibyte) refer to two different amounts. The IEC introduced the mebibyte (MiB) in 1998 to remove the ambiguity: 1 MiB = 1,048,576 bytes (1024^2), while 1 MB in the decimal (SI) sense = 1,000,000 bytes (1000^2). Operating systems like Linux and macOS now use MiB for binary values, while hard drive and SSD manufacturers use MB in the decimal sense. For most everyday purposes people use MB loosely to mean either, so always check which system the context refers to.

How do I convert megabytes to megabits?

Multiply megabytes by 8 to get megabits. There are 8 bits in every byte, so 1 megabyte = 8 megabits. This conversion is the same regardless of whether you use binary or decimal megabytes. This matters for internet speeds: an ISP may quote 100 Mbps (megabits per second), which is 12.5 MB/s (megabytes per second) for file transfers. A 100 MB file would take 8 seconds to download at 100 Mbps.

Byte Conversion Calculator

This calculator converts any value between the units used to measure digital storage and data - bits, bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes. It matters because there are two different definitions of these units in everyday use: operating systems, RAM specifications and file managers use the binary system, where each step up is a multiple of 1,024, while hard drive manufacturers, SSD makers and internet providers use the decimal system, where each step is a multiple of 1,000. This is why a "1 TB" drive shows as roughly 931 GiB in Windows, and why file sizes on screen never quite match what the box promised. You enter a value and choose which unit it is currently in, from bits through to petabytes in either system, then set your preferred display precision and choose fixed decimal or scientific notation for very large or small numbers. The calculator instantly returns the equivalent in bits, bytes, and megabytes in both binary and decimal form as headline results, plus full conversion tables covering every unit in the binary (base 1024) and decimal (base 1000) systems side by side. Use it to check download times against advertised broadband speeds, work out the real usable storage on a new drive, convert RAM or file sizes for a spec sheet, or simply settle an argument about what a gigabyte actually is.

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Standard reference IEC 80000-13 binary prefixes (kibibyte, mebibyte, etc.) and SI decimal prefixes.

1. Enter Value

Value to convert

From unit

2. Options

Display precision (decimal places)

Number format

Conversion Results

Bits

Bytes

Megabytes (binary)
-
MB / MiB

Megabytes (decimal)
-
MB (SI)

Binary System (Base 1024)

Unit	Symbol	Value	Bytes

Decimal System (Base 1000)

Unit	Symbol	Value	Bytes

How Byte Conversion Works

Digital storage is measured in bytes, where each byte contains 8 bits. A bit is the smallest unit of digital information and can hold either a 0 or a 1. All file sizes, memory capacities, and storage devices are ultimately measured in multiples of bytes.

There are two systems for expressing byte multiples, which differ in what "kilo", "mega", and "giga" mean:

Binary System (Base 1024)

Computers work in base 2, so the natural multiplier is 2 to the power of 10 = 1,024. Operating systems (Windows, macOS, Linux), RAM specifications, and many file managers use this system. The IEC introduced specific names to remove ambiguity: kibibyte (KiB), mebibyte (MiB), gibibyte (GiB) and so on, though many people still say "kilobyte" or "megabyte" when they mean the binary values.

Unit	IEC Symbol	Bytes	In bytes
Bit	b	1/8	0.125
Byte	B	1	1
Kilobyte (Kibibyte)	KB / KiB	1024^1	1,024
Megabyte (Mebibyte)	MB / MiB	1024^2	1,048,576
Gigabyte (Gibibyte)	GB / GiB	1024^3	1,073,741,824
Terabyte (Tebibyte)	TB / TiB	1024^4	1,099,511,627,776
Petabyte (Pebibyte)	PB / PiB	1024^5	1,125,899,906,842,624

Decimal System (Base 1000)

Hard drive manufacturers, solid-state drive (SSD) manufacturers, and network equipment vendors use the SI (International System of Units) decimal prefixes where 1 kilo = 1,000. This is why a "1 TB" drive shows as roughly 931 GiB in Windows: Windows uses binary GiB (1,073,741,824 bytes) while the manufacturer counts in decimal GB (1,000,000,000 bytes).

Unit	Symbol	Bytes	In bytes
Kilobyte	kB	1000^1	1,000
Megabyte	MB	1000^2	1,000,000
Gigabyte	GB	1000^3	1,000,000,000
Terabyte	TB	1000^4	1,000,000,000,000
Petabyte	PB	1000^5	1,000,000,000,000,000

Worked Example: 1 Byte

Starting with 1 byte (the default), the calculator converts to all units as follows:

Bits: 1 x 8 = 8 bits
Bytes: 1 byte
Kilobytes (binary): 1 / 1,024 = 0.0010 KB
Megabytes (binary): 1 / 1,048,576 = 0.0000 MB
Kilobytes (decimal): 1 / 1,000 = 0.0010 kB
Megabytes (decimal): 1 / 1,000,000 = 0.0000 MB

These match the default output of the calculator above with precision set to 4 decimal places.

Common Uses

Internet speeds: ISPs quote speeds in megabits per second (Mbps). To find your file download speed in MB/s, divide by 8. A 100 Mbps connection downloads at up to 12.5 MB/s.
Storage capacity: Hard drives and SSDs use decimal gigabytes. A 1 TB drive holds approximately 931 GiB as shown by Windows.
RAM: Memory is always specified in binary gibibytes (GiB), though usually labelled GB.
File sizes: Operating systems typically report file sizes in binary kibibytes or mebibytes (shown as KB or MB).

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Method and sources: Binary prefix values follow IEC 80000-13:2008 (kibibyte = 2^10 bytes, mebibyte = 2^20 bytes, etc.). Decimal prefix values follow the International System of Units (SI) where kilo = 10^3, mega = 10^6, and so on. The bit-to-byte relationship (1 byte = 8 bits) is defined by the standard ASCII/Unicode encoding convention.

This calculator converts between common digital storage units using standard binary (base-1024) and decimal (base-1000) systems. Results are rounded to the selected precision. For very large or very small values, use scientific notation mode to see full precision.