How to Calculate Mbps

By Sean Lancaster

Communication between computers occurs at varying speeds --- measured in bits per second (bps) --- depending on the networking hardware's capabilities. File sizes are measured in bytes, with one byte equaling eight bits of information. Typical files sizes range from kilobytes (KB) to megabytes (MB) to gigabytes (GB). The size of the file and the elapsed transfer time measures the network's bps speed. The transfer of high MB or GB files works better on networks rated at Mbps speeds. Converting the file size to bits and not bytes is required to measure the speed accurately.

Step 1

Express the size of the computer file in bytes. The prefixes kilo-, mega- and giga- refer to multiples of 1,024, rather than 1,000.Assume a file is 32 MB in size. Expressing the file size in bytes would be 32 X 1,024 X 1,024 = 33,554,432 bytes.

Step 2

Multiply the file's number of bytes by eight to find the number of bits.Continuing with the same example file size, the file would contain 33,554,432 bytes X 8 bits/byte = 268,435,456 bits.

Step 3

Divide the number of bits transferred by the elapsed time, in seconds, it takes to transfer the file. Convert minutes into seconds by multiplying the number of minutes by 60.Continuing the example, assume the transfer required 26 minutes and 50.60 seconds.26 x 60 = 1,560 seconds1560 + 50.60 = 1,610.60 seconds268,435,456 / 1,610.60 = 166,667.99 bps

Step 4

Express the speed as Mbps by dividing bps by 1,000,000.Using the example, the network runs at a speed of 0.17 Mbps.