How this calculator works
A kilobyte is either 1,000 bytes or 1,024 bytes depending on which prefix convention is being used, and the same split applies to the megabyte. The decimal convention follows the SI prefixes: kilo means 1,000 and mega means 1,000,000. The binary convention uses the IEC prefixes kibi and mebi for 1,024 and 1,048,576, though many programs and people still write kB and MB for those values. This page keeps the two answers separate: MB always means a decimal megabyte and MiB always means a binary mebibyte.
Formula
megabytes (decimal) = kilobytes / 1,000. mebibytes (binary) = kilobytes x 1,000 / 1,048,576 = kilobytes / 1,048.576. Going the other way, 1 MB = 1,000 kB and 1 MiB = 1,024 KiB.
Worked example
1,000 kB is exactly 1 MB, and 1,000 kB is 0.953674 MiB because 1,000 x 1,000 / 1,048,576 = 0.953674. 2,048 kB is exactly 2 MiB, and it is 2.048 MB. 500 kB is 0.5 MB and 0.476837 MiB.
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Frequently asked questions
Which answer should I use for a file size?
Use the decimal answer when the size comes from a storage maker, a network transfer or a file manager that shows SI units. Use the binary answer when a program reports MiB or when you are comparing with a 1,024 based tool. The byte count is the only unambiguous value.
Why is 1,000 kB not equal to 1 MiB?
A mebibyte is 1,048,576 bytes, which is larger than a decimal megabyte of 1,000,000 bytes. So 1,000 kB, exactly one million bytes, is slightly less than one MiB.
Is a kB the same as a KB?
In practice people use both spellings for the same informal idea, but the correct SI symbol is kB with a lower case k. When precision matters, write kB for 1,000 bytes and KiB for 1,024 bytes.