How much data can you download per day? This calculator will show the number of bytes for lots of different bandwidths.
You can specify the amount of overhead to be taken into account. A realistic value for normal internet usage (average file size less than 25KByte) is 50% overhead.
In data communications only the Metric definition of a kilobyte (1000 bytes per kilobyte) is correct.
The binary definition of a kilobyte (1024 bytes per kilobyte) is used in areas such as data storage (harddisk, memory), but not for expressing bandwidth and throughput.