# Early morning sums on Broadband.

GRIDD 08:28 30 Sep 2008
Locked

At optimal speed how long should it take to download?

interzone55 08:51 30 Sep 2008

Technically it should take around 500 seconds, about 8 minutes 20 seconds, but that's if the site uploading the file can maintain the uplink speed.

GRIDD 09:02 30 Sep 2008

Thanks alan14 - I had thought that myself.

You divide your download speed by 8 and then divide that number into the size of the file?

20Mbps / 8 = 2.5MBps

1GB / 2.5 MBps = 409.6 seconds

In truth it took me nearly 95 minutes, from the Playstation Network, and it was in the early hours of the morning too.

95mins / 60 = 5700 seconds

1GB / 5700 = 0.18MBps is the speed I was getting?

Can someone confirm if my sums are right or wrong?

interzone55 09:13 30 Sep 2008

No, you're sums are correct - except you've assumed that a 20mb line will give you 20mb of download, you will never get that due to network over heads, the best you can expect in the real world is about 16mb.

The biggest factor determining the speed of a download is the upload speed from the web-server.

Even the biggest, most popular websites only sit on 100 or 200mb pipes, and this is spread across all users. A small download may peak at 300 or 400KB/s (2.4 or 3.2mbs), but when downloading a big ISO file many factors, including the way Windows handles big files, will conspire to slow the whole process down...

Weskit 10:04 30 Sep 2008

But why, when I watch a download speed, does it always reduce as the d/load progresses?

GRIDD 10:14 30 Sep 2008

thanks again alan14

interzone55 11:28 30 Sep 2008

There's no easy answers to that question, I used to have a rough idea why it happens, but I've forgotten the answer, and Google has just confused me further.

If you really want an answer I suggest you ask in the Helproom...

Weskit 18:26 30 Sep 2008

alan14
Thanks, not the end of the world, just curious. (Apologies to GRIDD)

Stuartli 20:42 01 Oct 2008

I use FreshDownload with an "up to 8MB" TalkTalk broadband service - I generally reckon on downloading at the rate of around 725-850kbps per second from a good server.

Best speed has been 952kbps to date (FreshDownload shows the download speed and its variations).

A 20MB download normally takes around 30-40 seconds on average.

When I think back to dial-up days and 5 to 7kbps speeds on a good day (even with FD), I wonder how I ever put up with it...:-)

GRIDD 09:43 18 Oct 2008

Since this post I now get between 16 and 18meg - currently downloading at 2.2MBps.....

This thread is now locked and can not be replied to.

Elsewhere on IDG sites

Alienware 17 R4 2017 review

Is this the future of VR and AR?