When you need this conversion
Checking whether an image, PDF or document fits an upload form. Many forms quote their limit in MB while your file manager shows KB, so converting avoids a rejected upload.
Decimal vs binary
- 1 kB = 1,000 bytes; 1 MB = 1,000 kB
- 1 KiB = 1,024 bytes; 1 MiB = 1,024 KiB
Web servers, browsers and most operating systems except Windows use decimal. Windows shows binary sizes with decimal labels, so a 1,000,000-byte file appears as 976 KB there.
Typical sizes
- A short text email: 5–50 KB
- A web-optimized JPEG: 50–300 KB
- A phone photo: 2,000–5,000 KB (2–5 MB)
- A 10-page PDF with images: 500–3,000 KB
Common mistakes
Ignoring the unit a form uses. “Max 2 MB” might mean 2,000,000 bytes or 2,097,152 bytes. If a file is close to the limit, compress it a little further.
Confusing kb (kilobits) with kB (kilobytes). A lowercase b means bits, which are eight times smaller.
Bigger files? Use MB to GB.