Calculate Download Time:
Once upon a time, downloading a file from the internet to a computer meant doing nothing (really, nothing!) but waiting for the download to finish before any further computer work or play could be resumed. Those days are over. Today’s multi-tasking computers can download a file while you’re doing 17 other things, all on the same computer at the same time. Whew!
Even though you can stay occupied or entertained while waiting on a download, it may be good to know how long a download can be expected to last. In minutes, not bytes.
Download speed is affected by three factors:
Your modem – No matter how fast the data is coming at you, it can only get there as fast as your modem can process it.
Your telephone line (if the computer is hard-wired to a land line) – As with the modem, data zipped through cyberspace at the speed of light can only get to you as fast as your telephone system can process it. A super clean phone line, free from as much interference (extension cords, answering or fax machines, etc.) as possible, will enable fastest transmission speeds. Portable wireless modems bypass the telephone line, connecting a computer directly from the modem to the ISP but process speed remains dependent upon how fast the modem can process data.
Your ISP – Your Internet Service Provider (ISP) advertises the highest transmission rates possible but, again, speed depends on how quickly all the data can be processed as it’s routed through the many processing points between the original data and your computer. The advertised speed is the highest possible but the reality is that you’ll probably see speeds fluctuating at slower than maximum rates.
The chart below provides an excellent tool to calculate download time in three easy steps:
—Begin by noting the size (in kilobytes [KB] or megabytes [MB]) of the file being downloaded.
—Then look below this number to the “Your Connect Speed” column. The numbers here represent the most common data transmission speeds available. These speeds will be clearly indicated on your modem and in the data you receive from your telephone carrier and ISP.
—Divide your file size by the connect speed and fill in the corresponding line in the “Download Time” column.
The download time you’ve just calculated is quite accurate but do allow a little wiggle room, especially if downloading something on deadline. Processing speed – be it of the modem, telephone carrier, or ISP kind – varies by the second, depending on the type and complexity of data being downloaded and on how many other people are using networked computers at the same time.
Why do other people matter? Each ISP router can process a specific amount of data and customers like us get our data routed together at various points along the way, just like everybody living on one street gets all the street’s mail routed together in one mailman’s bag. The fuller the mailbag, the longer it takes the mailman to get from one end of the street to the other.
Fluctuations in processing speed are especially evident when many homes in a neighborhood use the same ISP (ATT, Verizon, and the like). Little Suzie’s homework may seem to be a short and sweet download but next door Mr. Jones may be trying to watch a streaming version of “War and Peace.” Suzie’s homework may download slower than anticipated because so much bandwidth is going into Mr. Jones’ movie but he’ll likely experience some glitches in transmission to make room for Suzie’s document. Both files (homework and movie) will get where they need to go but either may download a little slower than the fastest advertised rate of transmission.