FilesCalcs

MB to KB converter

Convert file sizes between bytes, KB, MB, GB and TB. Switch between decimal units (1,000) and binary units (1,024) to match what your computer shows.

Worked out in your browser. Nothing is sent anywhere.

Counting system
Result
In the other system

Most upload limits and storage makers use decimal. Windows shows sizes in binary but labels them KB, MB and GB.

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How to use the MB to KB converter

  1. Type the size you want to convert.
  2. Choose the unit it is in and the unit you want.
  3. Pick decimal (1,000) or binary (1,024) units.
  4. Read the converted size.

1,000 or 1,024: why there are two answers

In decimal units, 1 KB is 1,000 bytes and 1 MB is 1,000 KB. This is the standard SI meaning, and it is what drive makers and macOS use.

In binary units, 1 KiB (kibibyte) is 1,024 bytes and 1 MiB is 1,024 KiB. Windows File Explorer counts this way but still writes "KB" and "MB", which is where the confusion comes from.

  • 1 MB = 1,000 KB (decimal) or 1 MiB = 1,024 KiB (binary)
  • 2.5 MB = 2,500 KB
  • 1 GB = 1,000 MB = 1,000,000 KB
  • 1 TB drive = 1,000,000,000,000 bytes, which Windows shows as about 931 GB

That last one is why a new hard drive seems to be missing space. Nothing is missing; the same bytes are counted in bigger units.

Which one does a "100 KB" upload limit use?

It could be either, and forms rarely say. A file of 102,400 bytes is exactly 100 KB in binary units, and Windows will show it as 100 KB, but it is 102.4 KB in decimal units and would fail a limit set at 100,000 bytes.

The safe approach is to aim a little under the limit. For a 100 KB limit, a file of 95 KB or less passes either way. For a 2 MB limit, stay under about 1,950 KB.

If your file is too big, the image tools on this site can shrink a photo to a target size, and it all happens in your browser.

Questions people ask

How many KB are in 1 MB?

1,000 KB in decimal units, which most upload limits and storage makers use. In binary units, 1 MiB is 1,024 KiB.

How do I convert KB to MB?

Divide by 1,000 for decimal units, or by 1,024 for binary. 750 KB is 0.75 MB in decimal units.

How many MB are in a GB?

1,000 MB in decimal units, or 1,024 MiB in a GiB in binary units.

Why does Windows show a different file size from my Mac?

Windows divides by 1,024 and macOS by 1,000, while both label the result KB or MB. The file is the same size; only the units differ.

Is a kilobyte 1,000 or 1,024 bytes?

Officially 1,000. The 1,024-byte unit is properly called a kibibyte (KiB), though many people and programs still call it a kilobyte.