Download Time Calculator · Guide

Mbps vs MB/s

Mbps measures megabits per second. MB/s measures megabytes per second. The capital B matters because one byte equals eight bits.

Divide by eight

To convert a decimal bit rate to the equivalent decimal byte rate, divide by 8. For example, 100 Mbps = 12.5 MB/s and 1 Gbps = 125 MB/s.

Multiply by eight

To convert decimal bytes per second back to bits per second, multiply by 8.

GB and GiB are different

1 GB is 1,000,000,000 bytes. 1 GiB is 1,073,741,824 bytes. A 1 GiB file therefore takes longer than a 1 GB file at the same transfer rate.

Why it changes download time

A mismatch between Mbps and MB/s introduces an eightfold error before any other assumption. A mismatch between GB and GiB introduces another unit difference. Keep both dimensions explicit.

Examples

At the mathematical line-rate limit, 1 GB at 100 Mbps takes 80 seconds. 1 GiB at the same 100 Mbps takes 85.89934592 seconds.