Computers · bandwidth

Data Transfer Time

How long a download or upload takes at a given speed — movies, games, backups.

also after a run of
Internet Speed Test →

Inputs

File size 15 GB

Speed 100 Mbps

Efficiency / overhead 90%

Real transfers rarely hit line rate (protocol overhead, Wi‑Fi, disk). 90% is a fair default.

Estimated time

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Ideal (100%)

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Effective speed

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Data

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Using this tool

Transfer time math

Time = size ÷ throughput. With speed in megabits per second and size in megabytes: seconds = (MB × 8) / Mbps. The Internet Speed Test’s “time to download a 4K movie” cards use the same formula.

Mbps vs MB/s

ISPs advertise megabits (Mbps). File sizes are usually megabytes (MB). Divide Mbps by 8 for ideal MB/s (100 Mbps ≈ 12.5 MB/s).

Why is my real transfer slower?

Wi‑Fi, congestion, server limits, disk write speed, and protocol overhead. Use the efficiency slider to model that.

Measure my real speed

Run the Internet Speed Test on this site, then paste the result here.

Idealised estimate. Not a guarantee of download time on a real link.