Convert file sizes between every unit.
Type a size or measure a file, and read it in every unit — in decimal or binary.
About the size of a feature film in HD.
In other units
- B
- 1,000,000,000
- KB
- 1,000,000
- MB
- 1,000
- TB
- 0.001
- PB
- 0.000001
Why 1 TB shows as 931 GB.
Drive makers count in thousands: a kilobyte is 1,000 bytes and a terabyte is a trillion. Windows counts in 1,024s and still writes “GB”, so the same trillion bytes shows up as 931 GB.
Neither is wrong — they’re two ways of counting. Switch between them to see both answers, or measure a file to read its exact size in bytes.
Both ways of counting
Decimal, the way drive makers and macOS count, and binary, the way Windows does.
A file’s exact size
Measure a file and read its size to the byte, not a rounded figure.
Measured on your device
Only the file’s size is read. The file isn’t uploaded, and its contents aren’t opened.
How to convert a file size.
- 01
Enter a size
Type a number and choose its unit, from bytes to petabytes — or measure a file.
- 02
Choose a base
Decimal counts in thousands, binary in 1,024s. Pick the one your drive or computer uses.
- 03
Read every unit
The other five units update as you type, with a rough idea of what that much data holds.
Questions.
How many MB are in a GB?
1,000 in decimal, the way drive makers and macOS count. In binary there are 1,024 MiB in a GiB, the way Windows counts. Switch the base to compare the two.
Why does my 1 TB drive show as 931 GB?
The maker counts 1 TB as 1,000,000,000,000 bytes. Windows divides that by 1,024 three times and still calls the result GB. Same drive, two ways of counting — switch to binary to see the 931.
What’s the difference between MB and MiB?
A megabyte (MB) is 1,000,000 bytes and a mebibyte (MiB) is 1,048,576. Windows counts in MiB but labels them “MB”; macOS counts in true megabytes.
Is my file uploaded when I measure it?
No. The converter reads the file’s size and nothing else — the file stays on your device.
