Best answer: It depends on your situation. The Chromecast is meant to connect directly to your TV's USB port. If your TV doesn't have a powered USB port, it's usually better to use the power adapter. The adapter will supply the power needed for the Chromecast to work.

Different rules for different setups

Chromecasts are incredible devices for streaming, and they require little setup, especially if your TV has a compatible USB port. The most straightforward way to set up Chromecast is to take the device out of the box and plug it directly into your HDTV and a powered TV USB port. If your TV doesn't have a powered USB port or doesn't have a free one, you may need to try another route. Thankfully, your Chromecast comes with a Micro-USB power adapter in the box, so you can still use it. Here are the steps for how to set up your Chromecast.

1. Plug one end of the Micro-USB power adapter into your Chromecast.
2. Plug the other end of the cable into the desired power supply.
3. Plug your Chromecast into any open HDMI input on your TV.

1. Plug the power supply into a powered USB port on the TV.
2. If a powered USB port isn't available, plug the Micro-USB power adapter attached to the Chromecast device into an external power supply.

Another reason to consider using an external power supply is that certain TVs don't provide power to all built-in USB ports while the TV is turned off. If Chromecast is plugged into a USB port that isn't powered, the device will automatically turn on and off with the TV, causing Chromecast to be recognized as a new source every time you turn the TV back on.

What about Chromecast Ultra?

While it's not necessary to use the USB power cable and power adapter included in the box with the standard Chromecast device, it is suggested you use those for optimal performance. That being said, it is necessary to use the provided cables with Chromecast Ultra, which won't work with any other USB cable, or any USB cable plugged into a TV. Here are the slightly different steps for setting up Chromecast Ultra.

1. Plug one end of the power supply into your Chromecast Ultra.
2. Plug the other end of the cable into an open outlet. You can also connect your Chromecast Ultra to an Ethernet network through the power supply port.
3. Plug your Chromecast Ultra into any open HDMI input on your TV.

Google TV is the exception

There are also some exceptions when connecting Chromecast with Google TV. Specifically, Chromecast with Google TV cannot be connected using a standard TV USB port because it uses too much power and will generate an error message. As such, you'll need to free up another outlet behind your entertainment center.

Google TV users can also choose to connect the Chromecast with Google TV device directly to a router to create a faster and more reliable connection in Wi-Fi dead zones. Google offers ethernet adapters for both Chromecast with Google TV (opens in new tab) and the regular Chromecast (opens in new tab) via the Google Store.

Start streaming

Once your Chromecast is properly connected, you should be able to see the Chromecast home screen. If you don't see it on your TV, use the Input or Source button on your TV's remote control to change the input until you see the Chromecast home screen.

Chromecast, 3rd Generation

Plug it in, stream it all!
Google Chromecast makes it super easy to stream your favorite online media on your HDTV using your computer or mobile device as a bridge. By simply connecting Chromecast to your home network using the provided cables, you can navigate apps like Netflix, Amazon Prime Video, and YouTube from your smartphone.

Chromecast with Google TV

Take your Google TV to the next level
Chromecast with Google TV is tailor-made to make streaming on your TV even better. The setup enables you to navigate apps like Netflix, Amazon Prime Video, and YouTube within seconds of powering on your HDTV.