I remember back in late 90s, just after the invention of DVD, somebody said – never underestimate the carrying capacity of a semi truck trailer loaded with floppy disks. I never did the math though, so here goes:

A typical semi truck trailer is 12.5x8x40 feet which gives 4000 cubic feet. This is 113,267,386 cubic centimeters. A floppy disk is 3.5 inch across, which would be 8.75 centimeters. Assuming thickness of 4 millimeters (it’s actually a little bit less), each floppy is 30.625 cubic centimeters.

So a semi can carry almost 3.7 million floppy disks (3,698,526) which amount to 5,201 GB or 5.07 TB of data. Looks like that guy was right.

Update: a comment pointed out an earlier quote about a station wagon loaded with 9 track tapes. 2400 feet 9-track tape is a 10.5 inch reel. Assuming thickness of 0.5 inch that amounts to 860 cubic centimeters. With folded rear seats, Audi A4 has 50.5 cubic feet of cargo space. That is 1,430,000 cubic centimeters. That amounts to 1662 9-track tapes.

Each tape holds 170MB (IBM 3400 series). All in all 275 GB

Update 2: Chevrolet Caprice has cargo capacity of 106.4 cubic feet. Filled with 9-track tapes would be 581 GB.