What this calculator does
Converting kilobytes to megabytes looks like simple arithmetic, but the factor to divide or multiply by depends on which convention is being used, and that is the thing that trips most people up. Operating systems such as Windows and macOS have traditionally reported file sizes using powers of 1,024 (since computers count in binary), while hard drive manufacturers, mobile data plans and network speeds are usually quoted in round powers of 1,000.
That means the same file can show two slightly different sizes depending on where you look: a 1,024,000-byte file reads as roughly 1,000 KB on a decimal scale but only about 977 KB on a binary scale. This calculator lets you pick the convention you need, rather than guessing, so kilobytes to megabytes and megabytes to kilobytes both come out matching the tool or spec you are comparing against.
The formula
On the binary convention, one megabyte is 1,024 kilobytes, matching how most desktop operating systems have historically reported file sizes. On the decimal convention, one megabyte is a round 1,000 kilobytes, matching how storage manufacturers and network providers usually advertise capacity and speed. Divide kilobytes by the chosen factor to get megabytes, or multiply megabytes by that same factor to get kilobytes back.
| Term | Meaning |
|---|---|
| KB | Kilobyte: 1,000 or 1,024 bytes, depending on the convention chosen. |
| MB | Megabyte: 1,000 or 1,024 kilobytes, depending on the convention chosen. |
| Binary convention | Uses powers of 1,024 (2^10), the convention historically used by desktop operating systems for on-disk file sizes. |
| Decimal convention | Uses round powers of 1,000, the convention used on drive packaging, spec sheets and data plans. |
The inputs explained
| Field | What to enter |
|---|---|
| Convert | Choose from Kilobytes to megabytes, Megabytes to kilobytes. |
| Value | The kilobyte or megabyte figure you want to convert. |
| Convention | Pick binary (1024) to match an operating system file size, or decimal (1000) to match a manufacturer or data plan figure. |
When to use it
Matching a file size shown by your computer
File managers on Windows and macOS have traditionally reported sizes in binary kilobytes and megabytes, so use the binary convention to reproduce the figure they display.
Comparing against advertised storage or data
Drive capacities and mobile data allowances are usually quoted in decimal units, so use the decimal convention when checking those figures against your own usage.
Explaining a size mismatch
If a downloaded file appears to be a different size than the website listed, converting both figures with the same, deliberately chosen convention usually accounts for the difference.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How many megabytes is a range of kilobyte values?
Common kilobyte figures converted to megabytes using the binary factor.
| Kilobytes (KB) | Megabytes (MB) | Convention used |
|---|---|---|
| 512 | 0.5000 MB | Binary (÷1024) |
| 1024 | 1.000 MB | Binary (÷1024) |
| 2048 | 2.000 MB | Binary (÷1024) |
| 5120 | 5.000 MB | Binary (÷1024) |
| 10240 | 10.000 MB | Binary (÷1024) |
| 51200 | 50.000 MB | Binary (÷1024) |
How does the same value differ under each convention?
A single kilobyte value shown against both the binary and decimal convention, to see the size of the gap.
Questions
Why do file sizes look different on different devices?
One common cause is that some systems calculate megabytes as 1,024 kilobytes while others use a round 1,000. The underlying file has not changed size, only the arithmetic convention used to describe it, which is exactly what this calculator lets you switch between.
Is a megabyte to kilobyte conversion the reverse of kilobyte to megabyte?
Yes. Whichever factor is used for one direction (1,024 or 1,000) is the same factor used in reverse: divide kilobytes by the factor to get megabytes, or multiply megabytes by that factor to get kilobytes back.
Which convention should I use by default?
If you are matching a figure shown by an operating system’s file properties, binary (1,024) is usually correct. If you are matching a spec sheet, drive label or data plan, decimal (1,000) is usually what was advertised.
Is this the same as converting megabits to megabytes?
No, that is a different conversion. Megabits to megabytes involves dividing by 8 to convert between bits and bytes, which is unrelated to the 1,024-versus-1,000 scaling question this calculator handles between kilobytes and megabytes.
For a bits-versus-bytes conversion instead of a scale conversion, see the megabits to megabytes calculator.