Computers & Laptops

Download Time Calculator

How long a download takes at your real connection speed, with Mbps and MB/s kept apart.

4 inputs Free, no sign-up

Your figures

From a speed test rather than from the bill. Advertised speeds are a ceiling, and what you get depends on the time of day, the server and your Wi-Fi.

Try an example

Result

Your result

Enter your figures and the result appears here.

Estimates only. Rates, fees and specifications change. Confirm against the official source before you rely on a figure — see our disclaimer.

About this calculator

A 100 Mbps connection downloads at 12.5 MB/s at best. Connections are sold in megabits and files are measured in megabytes, and the factor of eight between them is why a "fast" connection can feel slower than expected.

Enter the file size and the speed a test actually gives you — not the figure on the bill.

How to use this calculator

  1. Enter the file size.
  2. Run a speed test and enter the download figure it reports.
  3. Check the unit. A speed test usually reports Mbps; a browser's download panel usually shows MB/s.

The formula

Time = File size in bytes / Speed in bytes per second

1 Mbps = 125,000 bytes per second
SymbolMeaningUnit
File size How big the download is GB or MB
Speed Your real download speed Mbps

Worked example

A 700 MB file on a 50 Mbps connection:

700 MB    = 700,000,000 bytes
50 Mbps   = 6,250,000 bytes per second
Time      = 112 seconds = 1 minute 52 seconds

Notes and limits

  • Advertised speed is a ceiling, not a promise. Contention on a shared line, the time of day and the server at the other end all reduce it.
  • Wi-Fi is often the bottleneck rather than the connection. A speed test over Wi-Fi measures the weaker of the two.
  • Protocol overhead takes a few per cent before anything else does.
  • A download that stalls and resumes averages well below the peak, which is why a real download usually takes longer than this.
  • For the other direction, the upload time calculator uses the same arithmetic with the upload speed.

What this calculation assumes

  • The speed is assumed sustained for the whole download, which it rarely is.
  • Overhead, contention and server-side limits are not modelled.
  • No connection speeds are stored in this page - the figure is the one you measured.

Frequently asked questions

How long will a 1 GB download take?

On a 50 Mbps connection, about 160 seconds at best. On 100 Mbps, about 80. Both assume the full speed is sustained, which is optimistic.

Why is my download slower than my connection speed?

Because the advertised figure is a maximum under ideal conditions. Wi-Fi, contention, the server's own limits and protocol overhead all take a share, and a download rarely holds the peak for its whole length.

Is 100 Mbps fast enough for 4K streaming?

Streaming is a sustained rate rather than a total, so it is a different question from this one. What this page will tell you is how long a file of a given size takes at a given speed.

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