If your disk has standard 512K byte sectors, you can calculate the free space (FS) required as follows:
1. Take the size of the volume, in bytes, and divide by 100. If this value is less than 1,048,576, use 1,048,576. If the value is larger than 4,194,304, use 4,194,304.
2. Add the size of the volume in bytes, divided by 803.
3. Add the number of files and directories that are on the volume, multiplied by 1,280.
4. Add 196,096.