Cool Fast Internet Download Speed Test Cool Fast Internet Download Speed Test Copyright © 2017-2026 Jerry Jongerius · Contact Us Works on any HTML5 device: This speed test works on virtually all desktops, tablets, cell phones, etc. There is no Java, no Flash, and no other plugin. The only requirement is HTML5, which ALL modern devices support. How the speed test works: This web page uses HTML5+JavaScript to download a large file from 'the cloud', recording the download progress and presenting that information to you in a very easy to understand graph. The test runs for 20 seconds, and then automatically stops. To restart the test, refresh the web page. To stop the test early, close the web page. If your connection is fast enough to completely download the large file, the download restarts (seen in the graph by a vertical red line). CloudFlare CDN: This speed test is hosted on the CloudFlare CDN. Your web browser will automatically connect to the nearest data center (displayed at the bottom of the chart) in the CloudFlare network (status). Troubleshooting: Are you not seeing the speed you expected? The speed reported is based upon actual downloaded bytes at the application (not network) level. Avoid wireless connections and instead try a wired connection. Or better yet, connect directly to your modem (eliminate any routers). Note that TCP/IP over Ethernet is around 95% efficient (1460/1538, or (1500-20-20)/(1500+38)). Namely, 5% of raw network speed is overhead and wasted by IP and network protocol overhead. Wireless connections are only 50% (in some cases, up to 70%) efficient. (eg: if your wireless connection is 150Mbps, your max throughput is around 75Mbps to 99Mbps). If you must use wireless, use high speed 802.11ac, which uses the 5 GHz band (avoid 802.11a/b/n in the 2.4 GHz band due to interference problems, as simply using a microwave can destroy performance). How some speed tests game the system: Virtually all speed tests 'game the system' by opening multiple connections to the server. That is a good method to find your maximum speed, because it works around many network issues (packet loss; per socket throttling; RWIN bugs; router bugs; etc). However, if you want to check your speed and check the reliability of your network, run a speed test (like this ***********) that intentionally only uses a single download socket. If you get great results, you know your network is in great shape! See ************************, which discusses that some Netgear routers have a single socket WAN to LAN throughput on port 80 bug that might limit throughput to around 400Mbps! Other HTML5 Speed Tests: There will always be Internet congestion issues somewhere. Always test your speed using multiple speed tests. Here are some: Speed TestProtocolPortSocketsNotes Cool Fast Speed Testhttp or https80 or 443singleadd '?multi=yes' to URL for multiple socket test Google Fiberhttps3xxxmultiple Comcasthttp502xmultiplewas Flash, but now is HTML5 Cloudflarehttps443single Netflixhttps443multiple CacheFlyhttp or https443multiple PC Magazinehttp8080multiplewebsockets download Spectrumhttp8080multiple Mediacomhttp8080multiple ATThttp8080multiplecan also test the speed between your AT&T Wi-Fi gateway and the Internet
