Bytes to kilobytes:
divide by 1,000

How many bytes are in a kilobyte?

In decimal units, 1 kilobyte (KB) is 1,000 bytes. The converter on this site uses these decimal units, where the prefix kilo means exactly one thousand, the same as in kilometre or kilogram. So 1,000 bytes is 1 KB and 500 bytes is 0.5 KB.

Some software counts in powers of two instead. In that system 1,024 bytes is called a kibibyte (KiB). The two are close but not identical, and knowing which one a program means explains most of the small mismatches between file sizes shown in different places.

The bytes to KB formula

1. 1Write the size in bytes.
2. 2Divide by 1,000 (move the decimal point three places left).
3. 3Check that the result is a thousand times smaller than the byte count.

Chart: bytes to KB

A handy picture: a plain English character in basic ASCII text takes 1 byte, so roughly a thousand characters, about a short paragraph, come to around 1 KB of plain text.

Kilobytes versus kibibytes

Kibibyte (KiB) was introduced to name the 1,024-byte unit unambiguously. Operating systems and storage vendors have not always agreed on which to display, so the same 3,200-byte file can appear as 3.2 KB in one tool and about 3.13 KiB in another.

A second worked example: a 3,200-byte configuration file is 3,200 ÷ 1,000 = 3.2 KB in decimal units. Divide by 1,024 instead and you get 3.125 KiB. Neither is wrong; they measure with different rulers.

More examples: small files and exact sizes

Round binary sizes make a good test. A file of exactly 4,096 bytes is 4.096 KB in decimal units, but 4,096 ÷ 1,024 = 4 KiB exactly, which is why people who work with memory prefer the binary unit. A file of 64,000 bytes is a tidy 64 KB in decimal units, and one of 12,800 bytes, such as a small web icon, is 12.8 KB.

Going up the ladder, 1,000,000 bytes is 1,000 KB, which is 1 MB in decimal units. Whenever a number of bytes is very large, convert to KB first, then divide by 1,000 again for MB, and you will rarely lose track of the decimal point.

Before you trust a displayed size, find out which unit the tool uses. If a download page says 100 KB and your file manager says 97.7 KB for the same file, nothing is broken: 100,000 bytes divided by 1,024 is 97.66, so the two tools simply divide by different numbers.

Common mistakes when converting bytes to KB

• Dividing by 1,024 and calling the answer KB. That result is in KiB.
• Confusing bits and bytes. One byte is 8 bits, and a lowercase b in 'kb' can mean bits in network speeds.
• Multiplying instead of dividing. A kilobyte is larger than a byte, so the KB number must be smaller.
• Slipping a decimal place. 800 bytes is 0.8 KB, not 0.08 KB.