Kilobytes to Bytes Converter

This converter multiplies by 1,000, so 1 KB = 1,000 bytes. Many people, and much software, expect 1,024. Both answers are in common use, and the converter keeps them apart: the binary kibibyte (KiB) is in the From list as its own unit.

The binary column is always 2.4% larger, whatever the value.

Config files, APIs and database columns usually want a plain byte count, while documentation tends to write "64 KB". Before you type a number in, work out which kilobyte the author meant. Round powers of two, such as 4,096 or 65,536, are a strong hint that the limit is binary.

Get it wrong and you're off by a few percent. Setting a 64 KB buffer to 64,000 when the code expects 65,536 leaves you 1,536 bytes short. For limits that must not be exceeded, the smaller decimal figure is the safe choice; for sizes that must be met, use the binary one.

Text size depends on the characters. In UTF-8 encoding, each plain English letter, digit or space takes 1 byte. Accented Latin letters such as é take 2 bytes, most Chinese and Japanese characters take 3, and most emoji take 4.

So a field limited to 4 KB, which is 4,000 bytes here, holds 4,000 plain ASCII characters but only 1,000 emoji. If users type in several languages, measure the limit in bytes, not characters.

A file's size in bytes is not always the space it takes up. File systems store data in fixed blocks, often 4,096 bytes each, and a file always occupies whole blocks. A 1 KB text file of 1,000 bytes still takes a full 4,096-byte block, and a 5,000-byte file takes two blocks, or 8,192 bytes.

Your file manager may show both numbers, as "size" and "size on disk". Use the first when a limit applies to the file itself, such as an upload form, and the second when you're working out how much a folder of many small files will fill a drive.