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Download time

A download’s duration, the connection’s actual rate or the downloadable size, with the Mbit/s to MB/s conversion made explicit.

Parameters

Result

Download time

0 h 22 min 13.3 s

Calculation
t = size / rate = 50 GB / 37.5 MB/s = 0 h 22 min 13.3 s
Rate
300 Mbit/s, that is 37.5 MB/s
Note

The download takes 0 h 22 min 13.3 s.

Calculation, assumptions and sources

OverviewDownload duration, actual measured rate or downloadable size.

Download duration, actual measured rate or downloadable size. Connections are advertised in megabits per second, files are counted in megabytes: a “300” fibre downloads at 37.5 MB/s at best. Every rate is given in both units.

Method & formulasduration = size / rate (same unit: bits)
duration = size / rate (same unit: bits)1 byte = 8 bits, so 1 MB/s = 8 Mbit/sactual rate = size / measured duration

All quantities are converted to bits; one byte is 8 bits.

Megabit per second (Mbit/s)
the unit of internet offers, in bits.
Megabyte per second (MB/s)
the unit of progress bars, in bytes. Dividing the offer by 8 gives the speed shown by the browser.
Actual rate
what really gets through, once the server, the Wi-Fi, the protocols and the other devices in the home are deducted. It is measured by timing a large file.
GB and GiB
the decimal gigabyte (10⁹ bytes) of product sheets and the binary gibibyte (2³⁰) of some systems. The gap is 7%; a “1 TB” drive shows 931 “GB”.
Validity domainThe calculation assumes a constant rate.

The calculation assumes a constant rate. A real download starts slowly and fluctuates with the server and the network, and protocols take 5 to 10% in headers, not modelled: the computed duration is a minimum. Sizes are decimal (1 GB = 10⁹ bytes), the convention of networks and commerce; binary units belong to the storage converter.

Reading the resultThe “actual measured rate” mode measures what the line delivers on a large download; a speed test measures a favourable instant towards an optimised server.

The “actual measured rate” mode measures what the line delivers on a large download; a speed test measures a favourable instant towards an optimised server. A 4 GB HD film takes 2 minutes on 300 fibre and 53 minutes on 10 Mbit/s ADSL; a 100 GB game takes an evening, even on fibre.