Whether you watch Netflix on your iPhone, iPad, Mac, Apple TV, or gasp a Windows PC, the quality of the video, how long it takes to load, and whether it stutters or skips is primarily determined by the bandwidth of your Internet connection. Netflix recommends 25 megabits per second (Mbps) of download speed for Ultra HD quality, 5 Mbps for HD, and 3 Mbps for SD. Netflix says that 1.5 Mbps is the lowest recommendation for a broadband connection, and notes that 0.5 Mbps is the minimum required, though I have generally found that it doesn’t really work on anything less than 1 Mbps.
So how do you tell what your real-world download speed is? Up to now, I would have recommended speedtest.net and for general testing of your speed, this is still a good option. It does require Flash, so please make sure that your player is up-to-date by checking System Preferences > Flash Player > Updates > Check Now or by going to adobe.com for a first time install on your Mac. If you are checking from a mobile device, you can get the SpeedTest.net app here.
The problem is that allegedly certain ISPs, despite the supposed protections of net neutrality, throttle Netflix traffic because it is the number one user of the internet in the US. In 2015, Netflix accounted for 37% of all internet traffic. If you want to find out if your ISP is throttling, check Netflix’s new fast.com Web site, which is a quick and easy way to determine how much bandwidth you get. This test uses Netflix servers as it source, so if your ISP is throttling Netflix, it will show up here. And if what you see doesn’t match with what you think you’re paying your Internet service provider for, call the ISP and make sure your connection is working properly. In my test, I got 8.1 Mbps at fast.com and 13.99 Mbps at speedtest.net, so there is a possibility that my Netflix is being throttled. I will be running additional tests and contacting my ISP if the speeds continue to diverge this much.