Uses javascript to get the browser to (first) download a tiny file repeatedly, with cache busting, measuring and reporting the time taken for each request. Then start 5 downloads of a larger file, in parallel if the browser supports this, and update the calculated speed as each download completes. The total data transferred and total time taken, minus the latency calculated in the first test, is the effective throughput reported in kilobits per second.
GPRS and 3G
The payload file is relatively small, 127Kb, so the overall time taken for the test should not be longer than a minute. Only a single download is done.
Wifi and 4G
The payload file is much larger, 2mb in size, and 3 parallel fetches are done.
Statistics
At the end of the test the average results are displayed according to their stated connection type.
More information
Updated information on this and other speed tests can be found here dslreports.com/speedtest or our tools page dslreports.com/tools
.