The speeds you get from any test reflect a best-effort scenario.
When you do an actual internet-related task, such as streaming or surfing the web, the performance will also depend on the servers of all parties involved (your service provider, the service you’re streaming from, etc.). These servers may or may not be capable of delivering your content as fast as your device is capable of receiving it.
To properly conduct a speed test:
1) Close any other apps, windows, programs, downloads…etc. BEFORE testing. The device you’re doing the speed test on should be the only device using your internet connection at the time of testing. If you have a wireless network, make sure all phones, laptops and gaming devices are off or disconnected from the network. Often times these devices automatically connect as soon as they are powered on and will impact your speed test results.
2) Make sure the device you’re using for the speed test is wired directly to your modem (i.e. not a wireless connection). Nearby wireless networks can severely degrade the signal strength of your Wi-Fi and give you an inaccurately low reading. This is particularly common in apartment complexes and neighborhoods where there may be several wireless networks within a smaller radius.
3) Check where the test server is located. If you’re allowed to choose the server location, you’ll want the server geographically closest to you.
4) Run the speed test several times over the course of a few days. This will give you an idea of your “average” speed and eliminate outliers.