Based on IBM's research, one bit takes between 1 and 62.5 million iron atoms on a normal hard disk. This application tries to estimate a medium weight for the input file, based on a value of (62.5 + 1) / 2 = 31.75 million iron atoms per bit.
cc -o fileweight fileweight.c
./fileweight some-file
Licensed under the terms of the WTFPL v2.