KB and kB refer to kilobyte - a unit of information or computer storage equal to either 1,024 bytes (210) or 1,000 bytes (103), depending on context.

MB refers to megabyte - a unit of information or computer storage equal to either 1,048,576 bytes (220) or 1,000,000 bytes (106), depending on context. A megabyte has approximately 1,000 (or 1,024 to be precise) kilobytes.

Comparison chart

KB versus MB comparison chart
Edit this comparison chartKBMB
Stands for Kilobyte Megabyte

Difference between kB and kb, MB and Mb

kb is kilobits and kB is kilobytes. While MB is megabytes, Mb refers to Megabits. 1 byte has 8 bits. File sizes are usually expressed in KB and MB whereas kb and Mb are often used to express data transfer speeds (such as a 54 Mbps wireless router or 3G or 4G connection speeds).

All units of information volume

A bit is the smallest unit of information. It is either a 0 or 1. A byte is the next smallest unit, and is equal to 8 bits. All other units of information are derived from bits and bytes, and represent a certain number of bits (or bytes).

Each unit contains a prefix and suffix. The suffix denotes whether the unit is representing bits or bytes; the prefix denotes how many bits/bytes are being conveyed. There are two types of prefixes:

Applying this pattern we can see that

Unit Base Power Value
Kilobit (Kb or kb) 1000 1 1000 bits
Megabit (Mb) 1000 2 10002 bits; or 1000 kilobits
Gigabit (Gb) 1000 3 10003 bits; or 1000 megabits
Terabit (Tb) 1000 4 10004 bits; or 1000 gigabits
Kilobyte (KB or kB) 1000 1 1000 bytes
Megabyte (MB) 1000 2 10002 bytes; or 1000 kilobytes
Gigabyte (GB) 1000 3 10003 bytes; or 1000 megabytes
Terabyte (TB) 1000 4 10004 bytes; or 1000 gigabytes
Kibibyte (KiB) 1024 1 1024 bytes
Mebibyte (MiB) 1024 2 10242 bytes; or 1024 kibibytes
Gibibyte (GiB) 1024 3 10243 bytes; or 1024 mebibytes
Tebibyte (TiB) 1024 4 10244 bytes; or 1024 gibibytes

Kbps vs. Mbps and Other Data Rate Units

Data rate units are represented as information per second. For example, Kilobits per second uses the symbol kbps, kbit/s or kb/s; Kilobytes per second is written as kB/s and Mbps stands for Megabit per second.

The notation follows this convention:

Symbol Name bit per second
bit/s bit per second 1
B/s byte per second 8
kbit/s kilobit per second 1,000
Kibit/s kibibit per second 1,024
kB/s kilobyte per second 8,000
KiB/s kibibyte per second 8,192
Mbit/s megabit per second 1,000,000
Mibit/s mebibit per second 1,048,576
MB/s megabyte per second 8,000,000
MiB/s mebibyte per second 8,388,608
Gbit/s gigabit per second 1,000,000,000
Gibit/s gibibit per second 1,073,741,824
GB/s gigabyte per second 8,000,000,000
GiB/s gibibyte per second 8,589,934,592
Tbit/s terabit per second 1,000,000,000,000
Tibit/s tebibit per second 1,099,511,627,776
TB/s terabyte per second 8,000,000,000,000
TiB/s tebibyte per second 8,796,093,022,208


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"KB vs MB." Diffen.com. Diffen LLC, n.d. Web. 7 Dec 2018. < >