MB to KB Converter
Enter a size in MB and the kilobyte value appears as you type. The default counts 1,024 KB per megabyte; tick the SI box to count 1,000 instead.
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Created by the Reeliy Editorial Team. Last updated: Oct 19, 2026
How many KB are in a MB?
A megabyte holds 1,024 kilobytes in the binary convention used by operating systems and file managers, and 1,000 kilobytes in the SI convention used by drive makers and by macOS. The converter applies 1,024 by default and 1,000 once you tick Use SI standard.
binary: KB = MB × 1,024
SI: KB = MB × 1,000SI writes the kilobyte with a lowercase k (kB); the capital K belongs to the binary habit.
Difference between MB and KB
Both are units of storage, one step apart. A kilobyte is the small unit: a short plain-text email or a tiny icon is a few KB. A megabyte is the next size up, where photos, songs and many documents live. Because KB is the smaller unit, converting from MB to KB always makes the number bigger.
Pay attention to capital letters. KB means kilobytes, while kb or Kb means kilobits, which are one eighth the size. If a figure is going to be compared with a network speed, double-check which one you have.
How to convert MB to KB
- Type the size in megabytes.
- Multiply by 1,024 (default) or by 1,000 (with Use SI standard ticked).
- Read the answer in kilobytes.
The result is rounded to four decimal places and shown without thousands separators, ready to be copied into a form or spreadsheet.
Example: an upload limit
A web form accepts attachments up to 2 MB. In binary counting that is 2 × 1,024 = 2,048 KB; in SI counting it is 2 × 1,000 = 2,000 KB. A photo that measures 2,010 KB therefore passes under the first rule and fails under the second, which is why file-size limits sometimes behave differently from what you expect.
Another quick one: 2.75 MB equals 2.75 × 1,024 = 2,816 KB (binary) or 2,750 KB (SI).
MB to KB conversion table
| Megabytes (MB) | Kilobytes, binary (× 1,024) | Kilobytes, SI (× 1,000) |
|---|---|---|
| 0.25 | 256 | 250 |
| 0.5 | 512 | 500 |
| 1 | 1,024 | 1,000 |
| 1.5 | 1,536 | 1,500 |
| 2 | 2,048 | 2,000 |
| 5 | 5,120 | 5,000 |
| 10 | 10,240 | 10,000 |
| 25 | 25,600 | 25,000 |
| 50 | 51,200 | 50,000 |
| 100 | 102,400 | 100,000 |
| 500 | 512,000 | 500,000 |
| 1,024 | 1,048,576 | 1,024,000 |
Common mistakes
- Using 1,000 for a binary quantity. If a tool reports sizes the way an operating system does, 1 MB is 1,024 KB, and multiplying by 1,000 under-counts by about 2.3%.
- Mixing KB with kilobits. Dividing or multiplying by 8 is what separates bytes from bits; it is not part of this conversion.
- Switching conventions mid-calculation. Convert everything with the same setting, then compare.
The opposite direction is covered by the KB to MB converter. To go further down the scale, use the MB to bytes converter; to go up, use the MB to GB converter.
Frequently asked questions
How many KB are in 1 MB?
1,024 KB by default (binary). With the SI option ticked, 1 MB is 1,000 KB.
How many KB are in 5 MB?
5 MB is 5,120 KB in binary counting and 5,000 KB in SI counting.
Is it KB or kB?
SI uses a lowercase k for kilo, so the decimal unit is written kB. The capital K is the common informal spelling and is used for both conventions.
Can I enter decimal megabytes?
Yes. Values such as 0.0001 MB are accepted, and the answer is rounded to four decimal places.
References
- NIST Reference on Constants, Units, and Uncertainty: Prefixes for binary multiples
- IEC 80000-13: Quantities and units, Part 13: Information science and technology
Cite this converter and page
If you use this page in your work, you can cite it as:
Reeliy Editorial Team. (2026). MB to KB Converter. Reeliy. https://reeliy.com/converters/convert-mb-to-kb“MB to KB Converter.” Reeliy, 2026, https://reeliy.com/converters/convert-mb-to-kb.