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File size calculator

Convert MB to KB Instantly

Type a megabyte value and see the kilobyte equivalent immediately, in both the binary convention (1 MB = 1024 KB, what operating systems and upload forms usually mean) and the decimal one (1 MB = 1000 KB, used by some storage marketing).

MB

1,024 KB (binary) | 1,000 KB (decimal)

Pure arithmetic in your browser | no file is touched or uploaded by a calculator.

The two conventions exist because computers address memory in powers of two while manufacturers market storage in powers of ten. Windows and most upload validators use binary, so 5 MB means 5,120 KB when a form checks your file.

Quick reference: 0.5 MB = 512 KB, 1 MB = 1,024 KB, 2 MB = 2,048 KB, 5 MB = 5,120 KB, 10 MB = 10,240 KB, 25 MB = 25,600 KB in binary terms.

When a portal states a limit in KB and your file manager shows MB, this calculator settles the comparison in a second. If the number is over the limit, the image compressor on this site can bring the file under it without any upload.

Which convention do upload forms use?
Almost all server-side validators use binary (1024), because that is what filesystem APIs report. Use the binary column when checking limits.
Why does my drive show fewer MB than advertised?
Marketing uses decimal gigabytes while operating systems report binary | a 500 GB drive shows about 465 GiB. Same physics, different rulers.
Can the calculator convert my file directly?
It converts numbers. To change an actual file size, use the image compressor with a KB or MB target | it also runs entirely in your browser.

How it works

  1. Type the MB value in the box.
  2. Read both conventions instantly below the input.
  3. Compare against your portal limit in KB.
  4. If over the limit, open the compressor with a KB preset from the chips below.

Related sizes and converters

KB to MBReduce in KBCompress to 1 MBImage Compressor

Frequently asked questions

Which convention do upload forms use?
Almost all server-side validators use binary (1024), because that is what filesystem APIs report. Use the binary column when checking limits.
Why does my drive show fewer MB than advertised?
Marketing uses decimal gigabytes while operating systems report binary | a 500 GB drive shows about 465 GiB. Same physics, different rulers.
Can the calculator convert my file directly?
It converts numbers. To change an actual file size, use the image compressor with a KB or MB target | it also runs entirely in your browser.