Advanced options
Megabytes (MB) measure size; megabits (Mbps) measure speed, and there are 8 bits in a byte, which is why a 100 Mbps connection downloads about 12.5 MB per second at best.
What The Download Time Calculator Works Out
- Download time: file size converted to megabits (8 bits to the byte) divided by the connection speed in megabits per second. A 100 Mbps line moves at most 12.5 MB a second, so a 10 GB file takes 13 min 20 sec at full speed and an 80 GB game about 1 hr 47 min.
- Real-world estimate: the same sum at 85% of headline speed, because Wi-Fi losses, busy servers, other devices and evening congestion all take a cut. A wired ethernet connection to the router is the single most effective speed-up for a big download.
- Typical downloads table: how long a 100 MB album, a 4 GB HD film, a 20 GB 4K film and an 80 GB game take at your speed. Use a measured speed-test figure rather than the advertised one for an honest answer; UK fibre-to-the-cabinet packages run about 35 to 70 Mbps and full fibre 150 to 900 Mbps or more.
- Speed entered in (advanced): accept the figure in MB/s (as download managers show it), Gbps or kbps instead of Mbps. The calculator converts to megabits internally so the bits-versus-bytes trap disappears.
- Real-world efficiency (advanced): override the 85% assumption. Wired full fibre often achieves 90% to 95% of the headline; a phone on busy 4G at the far end of the house may manage 30% to 50%.
- Number of files or devices (advanced): multiplies the data, for example three consoles each pulling the same 80 GB update, or a 20 GB backup to two cloud services. They share the one connection, so the time scales with the count.
- Compare with another speed (advanced): shows the time at a second speed and how much it saves, which is the honest way to judge whether a 500 Mbps or gigabit upgrade would change anything you actually notice.
- Must finish within (advanced): the reverse calculation: the speed in Mbps you would need to finish by the deadline after the efficiency factor, and how many times faster than your current line that is.
- Size counted in (advanced): Windows and many apps report sizes in binary units (1 GiB = 1,024 MiB), about 7% bigger than the decimal units broadband and storage adverts use. Choose binary if you copied the size from a file properties box so the time is not understated.
- UK connection types table (advanced): the realistic time for this download on ADSL, 4G, FTTC, 5G and full fibre tiers, so you can see at a glance which speed band moves the needle for files of this size.