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~2 minBit vs. Byte: What's the Difference?
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A bit is the smallest unit of digital data, a single 0 or 1, while a byte is a group of 8 bits that can represent 256 different values, enough for one letter of text. Internet speeds are quoted in bits per second (Mbps) but file sizes in bytes (MB), so a 100 Mbps connection downloads at most about 12.5 megabytes per second.
At a glance
| Bit | Byte | |
|---|---|---|
| Size | One binary digit: 0 or 1 | 8 bits |
| Values it holds | 2 values | 256 values (0 to 255) |
| Symbol | Lowercase b, as in Mb and Gb | Uppercase B, as in MB and GB |
| Typical use | Network and internet speeds (Mbps) | File sizes, storage and memory (MB, GB) |
| Everyday example | A 100 Mbps broadband plan | A 5 MB photo or a 128 GB phone |
Which should you use?
Bit
Bits are the unit for data transfer rates, so a broadband plan, a 4G speed test or a Wi-Fi router's rating is quoted in megabits or gigabits per second.
Byte
Bytes are the unit for amounts of stored data, such as a 3 MB song, a 2 GB film download or the 256 GB of storage in a phone.
Frequently asked questions
How do I convert Mbps to MB/s?
Divide by 8. A 100 Mbps plan delivers at most 12.5 MB per second, and a 40 Mbps plan about 5 MB/s. Real downloads are slightly slower because part of the bandwidth carries protocol overhead such as packet headers.
Is a kilobyte 1,000 or 1,024 bytes?
Officially, a kilobyte (kB) is 1,000 bytes and a kibibyte (KiB) is 1,024 bytes. Windows still counts in units of 1,024 while labelling them KB, MB and GB, which is why a 1 TB drive shows up as about 931 GB.
Why are there 8 bits in a byte?
The 8-bit byte became standard largely through IBM's System/360 computers in the 1960s. Eight bits hold 256 values, enough for upper- and lowercase letters, digits and symbols, and 8 is a power of two, which suits computer hardware.