Mac 911: Modem Speed Test

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It defies logic, but your 56K modem will never, ever reach a speed of 56 kilobits per second in North America (and many other delightful spots around the globe). That's partly because government regulations prohibit such modems from exceeding 53Kbps. In most cases, you'll be lucky if your modem tops out at around 48K. But how can you tell how fast your modem is going? Here's a hint: Not by looking at the status pane of Apple's Remote Access.

Remote Access reflects only the speed at which the modem initially connects. From that initial connection speed, throughput can ratchet down significantly. To better determine your modem's true connection speed--it's data transfer rate --try this method suggested by Apple:

Open an FTP client such as Fetch and log onto an FTP server that's either close-by (at a local university or users group, for example) or not terribly well trafficked (say, a university with a terrible collection of software or an extremely unpopular users group). Scout around until you find a compressed file around 500K and download that file, noting how long it takes to download.

Then use this formula to determine the average data transfer rate of that download: file size (in bytes) divided by download time (in seconds) times 9 equals your modem's average data transfer rate (bits per second). So, for example, a 500K file that takes three minutes (180 seconds) to download would work out this way:

500,000/180 x 9 = 25,000 or around 25Kbps.

This formula isn't perfect for a number of reasons--data may need to be re-sent due to errors, the file may actually be a bit larger or smaller than indicated by the FTP client, and the data transfer rate can vary during the download. Also, a single FTP download won't tell you the entire story. To get a better idea of how your modem really performs, you should repeat this test at different times of day with different FTP servers. After conducting the test numerous times, you'll have a reasonable idea of how fast your modem goes.

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