Eric, Very close, the actual density is 6250BPI (bits per inch) so it would be 6250 x 12in x 2400ft = 180,000,000 or 175.78 MB ( a MB is 1,024,000 bytes). We can use this calculation as bytes because the tape has 9 tracks 1 for each bit plus parity. But practically, I measured and found that on good tapes I consistently got 140MB. John Zoltak North American Mfg Co > -----Original Message----- > From: Eric Bender [SMTP:[log in to unmask]] > Sent: Thursday, August 13, 1998 2:56 PM > To: [log in to unmask] > Subject: Re: [HP3000-L] tape capacity > > At 11:18 AM 8/13/1998 -0700, Donna Garverick wrote: > >i guess this is an oldie but a goodie sorta question... > > > >how much information can a 2400' reel (yes, reel) of tape > >contain -- in theory. i guess, perhaps, the better question > >is -- does anyone remember the equation for calculating > >this? - d > > > >-- > >Donna Garverick Sr. System Programmer > >925-210-6631 [log in to unmask] > > > So, assuming no Inter-Record (or Inter-Block) Gaps, at 1600 BPI that > would be: > > 1600 x 12in/ft x 2400 = 46,080,000 bytes (46 MB) > > and at 6400 BPI it'd be 184,320,000 bytes (184 MB). > > So, with IRG's and labels and other overhead, actual values would be > less > than these theoretical calculations. > > Regards, Eric Bender > > PS. Someone check these calculations. Please!