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 | MB |
|---|---|---|
| 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:
- Kilo-, mega-, giga-, tera-, peta-: these are the prefixes most widely used. They denote aggregations in units of 1,000.
- Kilo- is 10001
- Mega- is 10002 i.e., 1 million
- Giga- is 10003 i.e., 1 billion
- Tera- is 10004 i.e., 1 trillion
- Peta- is 10005 i.e., 1 quadrillion
- Kibi-, mebi-, gibi-, tebi-, pebi-:these prefixes denote aggregations in units of 1024. Since computing uses a binary system, the totals for units of storage are always in powers of 2. 1024 is 210.
- Kibi- is 10241
- Mebi- is 10242
- Gibi- is 10243
- Tebi- is 10244
- Pebi- is 10245
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:
- Use lower-case b for bits and upper-case B for bytes. e.g. MB/s is megabyte per second and Mbps is megabit per second.
- K stands for kilo and may be used in upper or lower case. M stands for mega, G for giga, T for tera. So 1 Gbps is 1 gigabit per second. These units are aggregated in multiples of 1000.
- Ki stands for kibi, so KiB/s is kibibytes per second while Kib/s or Kibit/s is kibibit per second. Similarly Mi stands for Mebi, Gi for Gibi, and Ti for Tebi. The units are aggregated in powers of 2, specifically 210.
| 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 |
Celsius 
Nautical Mile 
Kilometer 
GMT
Comments: KB vs MB