Kilobytes to bytes:
multiply by 1,000

How many bytes are in a KB?

One kilobyte (KB) is 1,000 bytes. The prefix kilo means a thousand, exactly as it does in kilometre and kilogram, so converting KB to bytes means shifting the decimal point three places to the right.

The Calcylator converter uses these decimal units: 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes and so on. A second system, binary, counts in powers of two and uses the names KiB, MiB and GiB, where 1 KiB = 1,024 bytes. The two are covered further down.

The KB to bytes formula

A small text file of 7.2 KB is 7.2 × 1,000 = 7,200 bytes. Because there is only a power of ten involved, you never need a calculator for whole numbers, though the converter is handy for long decimals.

1. 1Write the size in KB, including any decimal part.
2. 2Multiply by 1,000, or move the decimal point three places to the right.
3. 3Add thousands separators so the long number stays readable.
4. 4Check that the byte figure is far larger than the KB figure.

Kilobytes to bytes conversion chart

These values use decimal kilobytes, where every row is the KB figure multiplied by 1,000.

The last row also shows that 1,000 KB make 1 MB, which is 1,000,000 bytes.

Where you convert kilobytes to bytes

Developers meet this conversion when a form or API states a limit in bytes but the design brief talks in KB. A profile picture capped at 200 KB is 200,000 bytes, which is the number a server setting such as a maximum upload size usually expects.

Web performance work uses it too. A page that sends 85 KB of CSS is sending 85,000 bytes, and comparing that against a budget written in bytes avoids mistakes. Embedded programmers go the other way and turn a byte count from a debugger into KB to see whether a program fits in memory.

KB versus KiB: the 1,024 catch

Many operating systems and older tools use 1,024 bytes per kilobyte while still printing the letters KB. The standard names for that binary unit are kibibyte and KiB. So 350 KiB is 350 × 1,024 = 358,400 bytes, about 2.4 percent more than 350 KB.

Common mistakes when converting KB to bytes

• Multiplying by 1,024 and calling the result KB. That is KiB, and the answer differs from the decimal figure.
• Dividing instead of multiplying. Bytes are the smaller unit, so the byte number must be bigger than the KB number.
• Mixing up KB and Kb. A lowercase b means bits, so 8 Kb equals only 1 KB.
• Dropping a zero. 1 KB is three zeros, so 25 KB is 25,000 bytes, not 2,500.