Convert network and file-transfer rates between bits and bytes per second, with decimal and binary prefixes. The Download time tab combines a file size with a connection speed and an explicit usable-throughput percentage.
How to use this calculator
For a speed conversion, enter the rate and select both units. A broadband speed labeled Mbps corresponds to the decimal Megabits per second option; MB/s means megabytes per second. For a transfer estimate, choose Download time, enter the file size and its unit, then enter the connection speed.
Advertised speed versus file throughput
Bits per second and bytes per second differ by a factor of eight before considering network overhead. Decimal Mbps and binary MiB/s also use different prefix factors. The dropdowns keep these distinctions visible.
Usable throughput describes how much of the stated connection rate is carrying your file data. At 100%, the estimate assumes ideal constant-speed transfer. At 80%, it assumes 20% is unavailable. This is an input assumption, not a speed test or a measured overhead model. If you enter an already measured payload speed, leave the percentage at 100% to avoid reducing it twice.
Examples
Converting an internet plan speed
100 Mbit/s = 12.5 MB/s, approximately 11.92092896 MiB/s. These are equivalent rates, not a promise of download performance.
A one-gigabyte download
At 100 Mbit/s, a 1 GB file takes an ideal 80 seconds. At 80% usable throughput, the same file takes 100 seconds. A 1 GiB file is larger and takes about 85.8993 seconds at the ideal rate.
Formula
bytes per second = bits per second / 8
effective bit rate = stated bit rate × usable percentage / 100
transfer seconds = file size in bits / effective bit rate
Precision and interpretation
The download estimate assumes a constant speed throughout the transfer. Server limits, Wi-Fi conditions, protocol overhead, retransmissions, disk speed, and pauses may change the actual duration. A zero-size file has zero modeled transfer time; this does not include connection setup. Speed must be positive. Values are rounded floating-point estimates.
Definitions and further reading
Unit and quantity reference provides the underlying definitions. The examples above are worked calculations for this tool.