Mijzelf did the math for you. Lets repeat. 1byte(B ) = 8bits(b ) (2^8=256 possibilities, enough for all characters), make it ~10 for the whole communication (sort of wrapping). 1kB = 1.000bytes and 1mB=1.000.000bytes (=~10.000.000b exchanged) also 1KB=1024 bytes and 1MB=1024KB, but lets round it. -80kbits/s is the speed, it's the volume per time. You want the time, so time=volume/speed but you have to use the same units for both values. (50.000.000 x 10bits) / (80.000bits/sec) = 6250sec = ~104min =~1h44'. This is pure theory, so use 1024 (twice) instead of 1000 and also add ~20% for real world. That gives ~2hours 11'. and so on, 1MB on 56k modem ~4min 1MB on 10Mb network ~1.2sec 10MB on 100Mb network ~1.2sec