File Size Converter
Bytes, KB, MB, GB, TB — binary or decimal.
Convert between bytes, KB, MB, GB, TB, and PB, with a choice of binary (1024-based, as your OS shows) or decimal (1000-based, as manufacturers advertise) conventions.
Binary vs. decimal units
| Unit | Decimal (1000-based) | Binary (1024-based) |
|---|---|---|
| Kilobyte | 1,000 bytes | 1,024 bytes (KiB) |
| Megabyte | 1,000,000 bytes | 1,048,576 bytes (MiB) |
| Gigabyte | 1,000,000,000 bytes | 1,073,741,824 bytes (GiB) |
| Terabyte | 1012 bytes | 1,099,511,627,776 bytes (TiB) |
Drive makers use decimal units. Windows uses binary units but labels them KB, MB and GB. macOS has used decimal units since 2009, so a Mac shows a drive's advertised size.
Why your new drive looks smaller
A "1 TB" drive holds 1,000,000,000,000 bytes. Windows divides by 1,024 three times and shows about 931 GB. Nothing is missing — it's the same amount of storage counted two ways.
| Advertised size | Shown in Windows |
|---|---|
| 256 GB | about 238 GB |
| 500 GB | about 466 GB |
| 1 TB | about 931 GB |
| 2 TB | about 1.82 TB |
Your usable space is a little lower again, because the operating system, recovery files and pre-installed apps take up room.
Typical file sizes
- A page of plain text: about 2–5 KB
- A smartphone photo: about 2–5 MB
- A 3-minute MP3 song: about 3–7 MB
- One minute of 4K phone video: roughly 300–400 MB
- A full HD movie download: about 2–8 GB
Need to know how long a file will take to download? Try the download time calculator.
Frequently asked questions
Why do file sizes look different in Windows vs. the actual file?
Windows uses 1024-based (binary) units labeled as KB/MB/GB, while storage manufacturers and some tools use 1000-based (decimal) units — this converter offers both so you can match whichever context you need.
What's the difference between MB and MiB?
MB (megabyte) technically means 1,000,000 bytes (decimal), while MiB (mebibyte) means 1,048,576 bytes (binary) — but "MB" is commonly used loosely to mean either, which is the source of most confusion.
How many MB are in a GB?
1,000 MB in the decimal system used by drive makers, or 1,024 MB in the binary system used by Windows. Use the Convention option above to switch between them.