Internet for Beginners/Calculating Download Duration


While I'm not exactly a "beginner," this seems to me to be a beginner-type question: I have Dial-up Internet Access with a download speed of about 30 Kbps (as measured by the Ookla Speedtest) and I need to download a 300 Mb file.  Am I safe in assuming that this download should be accomplished in about:
300,000 Kb / 30 Kb/sec  =  10,000 sec  =  2 hr 47 min - or am I being too simplistic in my thinking?

Hi Ed

I can see where you would come to that result.  I will explain this as best as I can, please reply to me if you need further clarification.

Your internet speed is actually measured in Kbps which is Kilobits per second, or 1000 bits per second.  This is different to a file size which is listed as kB meaning kilobyte .  A kilobyte is 1024 Bytes.

1 bit
8 bits = 1 byte
1024 bytes = 1 kilobyte
1024 kilobytes = 1 megabyte
1024 megabytes = 1 gigabyte

This means that you have sadly overestimated your internet speed.  Your download speed is listed as 30 kbps which means 30,000 bits per second, not bytes.  

Now for calculation, it would not be worth your time to convert the MB file size to bits for the purpose of working out the time to download.  The answer would give an exponential value and it's much easier to use an online time calculator.  I would recommend visiting this site - - which gives an approximation of the download time.  Now your download will be based on the server upload speed, your current download speed and available bandwidth.  With your listed download speed, I'm afraid this file will take just under 1 full day to download, around 23 hours.  

I hope I have explained this clearly.  It is a common misunderstanding that download speeds are directly related to file sizes and I can see how kbps would be confused with a kilobyte.  For future reference; a bit will be listed as a small 'b' and a byte should be listed as 'B'.  This means that a kb is a kilobit and a kB is a kilobyte.

Please reply if you would like some more information or clarification and good luck with your download!


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Steven Gibb


I can answer any question related to the internet. I will answer any question regarding the history of the internet to understanding how it works. I am willing to aid new users in understanding any aspect of the internet and can also help more advanced users with any problems they are having. I can also help with general networking and computer issues. If the question is related to information technology I will be able to help.


I hold two degrees related to computer science and engineering. I have volunteered in several libraries and schools with the aim of helping new users get to grips with computers and the internet.

European Advanced Computer Driving License Bsc Electronics (Product Design/Comp Architecture) BEng Digital Systems Engineering

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