Convert MB and KB instantly.
There are 1,024 kilobytes (KB) in one megabyte (MB) in the binary system used by Windows, RAM and most software. In the decimal (SI) system used by storage manufacturers and macOS, 1 megabyte = 1,000 kilobytes.
So when someone asks how many kilobytes are in a megabyte, the answer is almost always 1,024 KB — unless you are reading a hard drive label or a file size on a Mac, where 1 MB is 1,000 KB. Use the MB to KB Converter above to get both values instantly for any number.
Converting megabytes to kilobytes takes a single multiplication:
Example: 5 MB × 1,024 = 5,120 KB (binary), or 5 MB × 1,000 = 5,000 KB (decimal).
Why 1,024? Computers work in powers of two, and 210 = 1,024 — the closest power of two to 1,000. That is why one megabyte holds 1,024 kilobytes, and one kilobyte holds 1,024 bytes. In bytes, 1 MB = 1,048,576 bytes (binary) or 1,000,000 bytes (decimal).
Going the other way, a kilobyte is a small fraction of a megabyte:
To convert kilobytes to megabytes, divide the KB value by 1,024 (or by 1,000 for decimal). For example, 512 KB is exactly 0.5 MB in binary. Need the reverse calculation often? Try the Data Storage Converter.
| System | 1 MB equals | Where you see it |
|---|---|---|
| Binary (base 2) | 1,024 KB | Windows File Explorer, RAM, most apps and upload limits |
| Decimal (SI, base 10) | 1,000 KB | Hard drive and USB packaging, macOS Finder, network speeds |
Technically, the international standard (IEC) names the binary units kibibyte (KiB) and mebibyte (MiB), so 1 MiB = 1,024 KiB, while 1 MB = 1,000 KB. In everyday use, though, most people and operating systems still say "MB" and "KB" for the binary values. This difference is also why a "500 GB" drive shows less free space on Windows than the box promises.
| Megabytes (MB) | Kilobytes (Binary, ×1024) | Kilobytes (Decimal, ×1000) |
|---|---|---|
| 0.25 MB | 256 KB | 250 KB |
| 0.5 MB | 512 KB | 500 KB |
| 1 MB | 1,024 KB | 1,000 KB |
| 2 MB | 2,048 KB | 2,000 KB |
| 5 MB | 5,120 KB | 5,000 KB |
| 10 MB | 10,240 KB | 10,000 KB |
| 20 MB | 20,480 KB | 20,000 KB |
| 25 MB | 25,600 KB | 25,000 KB |
| 50 MB | 51,200 KB | 50,000 KB |
| 100 MB | 102,400 KB | 100,000 KB |
| 250 MB | 256,000 KB | 250,000 KB |
| 500 MB | 512,000 KB | 500,000 KB |
| 1,000 MB | 1,024,000 KB | 1,000,000 KB |
| 1,024 MB (1 GB) | 1,048,576 KB | 1,024,000 KB |
| Kilobytes (KB) | Megabytes (Binary, ÷1024) | Megabytes (Decimal, ÷1000) |
|---|---|---|
| 100 KB | 0.0977 MB | 0.1 MB |
| 200 KB | 0.1953 MB | 0.2 MB |
| 500 KB | 0.4883 MB | 0.5 MB |
| 512 KB | 0.5 MB | 0.512 MB |
| 1,000 KB | 0.9766 MB | 1 MB |
| 1,024 KB | 1 MB | 1.024 MB |
| 2,048 KB | 2 MB | 2.048 MB |
| 5,000 KB | 4.8828 MB | 5 MB |
| 10,000 KB | 9.7656 MB | 10 MB |
| File | Size in MB | Size in KB (Binary) |
|---|---|---|
| Smartphone photo | 3 MB | 3,072 KB |
| MP3 song (≈4 minutes) | 8 MB | 8,192 KB |
| Email attachment limit | 25 MB | 25,600 KB |
| App installer | 120 MB | 122,880 KB |
Many upload forms, job portals and government websites state limits in KB — for example "max 200 KB" for a photo or "max 2048 KB" for a PDF. Converting your file's MB size to KB tells you in seconds whether it fits or needs compressing first.
One megabyte contains 1,024 kilobytes in the binary system and 1,000 kilobytes in the decimal system. Windows and most software use 1,024.
One kilobyte is 0.0009765625 MB in binary (1 ÷ 1,024) or 0.001 MB in decimal (1 ÷ 1,000).
Both are used. 1,024 KB is the binary value used by operating systems and memory; 1,000 KB is the decimal SI value used by storage manufacturers and macOS.
A megabyte is bigger. One MB equals 1,024 KB, so a kilobyte is roughly one-thousandth of a megabyte.
Multiply the number of megabytes by 1,024 (binary) or 1,000 (decimal). For example, 3 MB × 1,024 = 3,072 KB.
A mebibyte (MiB) is always 1,024 KiB (binary), while a megabyte (MB) officially means 1,000 KB (decimal). In practice, many systems label mebibytes as "MB".
So, how many kilobytes in a megabyte? 1,024 KB in binary, 1,000 KB in decimal. Whether you are checking an upload limit, optimizing a website or comparing storage, the free MB to KB Converter on AlllinTools gives you both answers in one click — no sign-up, no downloads.