 Common seven-track densities started at 200 six-bit characters per inch (CPI), then 556, and finally 800.Nine-track tapes had densities of 800 (using NRZI), then 1600 (using PE), and finally 6250 (using GCR).This translates into about 5 megabytes to 140 megabytes per standard length (2400ft) reel of tape.