Google Cast is a wireless connection that sends video, audio, or your entire screen from your phone, tablet, or computer to a TV or speaker

Google Cast works by creating a direct link between your device and a Chromecast receiver (a small box plugged into your TV or a TV with Cast built in). When you tap the Cast button in an app, your device tells the Chromecast what to play. The Chromecast then streams the content directly from the internet or from your device, rather than your phone sending the video all the way through. This is why you can pause a show on your TV, lock your phone, and the video keeps playing—the Chromecast is doing the work, not your phone.

The connection happens over your home Wi-Fi network. Your phone and the Chromecast both need to be on the same Wi-Fi network to find each other. Once they connect, you control playback from your phone like a remote control, but the actual video or audio streams independently to the TV or speaker.

Key Takeaways

  • Google Cast sends content from your device to your TV or speaker over Wi-Fi, so your phone acts as a remote rather than streaming the entire video through it.
  • Your phone and Chromecast must be connected to the same Wi-Fi network to find and communicate with each other.
  • You control what plays using the Cast button in compatible apps like YouTube, Netflix, Spotify, and Google Photos.
  • Casting your entire screen (called screen mirroring) works differently than casting an app and uses more of your phone's battery.

What happens when you tap the Cast button

When you open an app like YouTube or Spotify and tap the Cast icon, your phone searches your Wi-Fi network for available Chromecast devices. A list appears showing the name of each Chromecast in your home. You select the one connected to your TV, and your phone sends a message to that Chromecast saying "play this video" or "play this song."

The Chromecast then goes directly to YouTube's servers (or Netflix's, or Spotify's) and starts streaming. Your phone is no longer in the middle—it is just sending commands like "pause," "skip," or "turn up the volume." This is why you can lock your phone, switch apps, or even turn it off and the video keeps playing on your TV. The Chromecast is the one actually pulling the content from the internet.

The difference between casting an app and screen mirroring

Casting an app (like Netflix or YouTube) and screen mirroring are two different things, and they work in opposite ways. When you cast an app, the Chromecast streams directly from the internet. When you screen mirror, your phone sends everything on its screen to the TV in real time, pixel by pixel. Screen mirroring is slower, uses much more of your phone's battery, and only works while your phone is awake and connected.

Screen mirroring is useful when you want to show photos, browse the web, or use an app that does not have a Cast button built in. But for watching movies or listening to music, casting the app is always better because it is faster and your phone can go to sleep.

Which apps and devices work with Google Cast

Most major streaming apps have a Cast button built in: YouTube, Netflix, Disney+, Hulu, Spotify, Apple Music, Google Photos, Podcasts, and many others. If an app has a Cast button, you can cast from it. If it does not, you can still screen mirror, but you will not get the same smooth experience.

Any device with a Chromecast receiver can receive a cast. This includes standalone Chromecast boxes (the small HDMI dongle), Google Chromecast with Google TV (which is a full streaming device), many smart TVs that have Chromecast built in, Google Home speakers, and some third-party speakers that support Cast. Check your TV's manual or the device's box to see if it has Chromecast built in.

How your phone finds the Chromecast on your network

Both your phone and your Chromecast use a technology called mDNS (multicast Domain Name System) to find each other on your home Wi-Fi. When you open an app and tap Cast, your phone broadcasts a message on the network asking "Is there a Chromecast here?" The Chromecast hears that message and responds with its name and what it is capable of playing.

This is why both devices must be on the same Wi-Fi network. If your phone is on your home Wi-Fi and the Chromecast is on a guest network, they cannot see each other. If you are away from home on cellular data, you cannot cast to a Chromecast at home—the connection only works on the same local network.

What happens to your privacy when you cast

When you cast an app, the content streams directly from the service (YouTube, Netflix, etc.) to your Chromecast. Google and the streaming service can see that you are watching, just as they would if you were watching on your phone or TV. Your phone is not relaying the video, so it is not recording or storing what you watch.

Your Wi-Fi router can see that data is flowing between your Chromecast and the internet, but it cannot see what you are watching—that data is encrypted. If someone else is on your Wi-Fi network, they cannot intercept your video stream or see what you are casting.

Why casting sometimes stops working

The most common reason casting fails is that your phone and Chromecast are not on the same Wi-Fi network. Check that both are connected to the same network name (SSID). If you have a 2.4 GHz and 5 GHz network with different names, make sure both devices are on the same one.

If they are on the same network and casting still does not work, restart your Chromecast by unplugging it for 30 seconds, then plugging it back in. Restart your phone's Wi-Fi by turning Wi-Fi off and back on. If the app you are trying to cast from is outdated, update it from your phone's app store. If none of that works, the app itself may be having problems—try a different app that supports Cast to see if the issue is with your Chromecast or the app.

When to call for help

If you have restarted both devices, confirmed they are on the same network, and updated your apps but casting still does not work, the problem may be with your Wi-Fi router, your internet connection, or the Chromecast hardware itself. Contact your internet provider to check your Wi-Fi signal strength, or contact Google support for help with the Chromecast device.

Google support can walk you through additional troubleshooting steps specific to your Chromecast model and help you determine whether the issue is a hardware problem that requires replacement. Your internet provider can also run diagnostics on your Wi-Fi network to rule out connection problems on their end.

Frequently Asked Questions

Can I cast from my computer to my TV?

Yes. On a Windows or Mac computer, open Chrome and click the three-dot menu, then select "Cast." You can cast a tab, your entire screen, or a file. The process is the same as casting from a phone—both devices need to be on the same Wi-Fi network.

Does casting use a lot of data?

Casting an app uses whatever data the app would normally use—if you are streaming 4K video on Netflix, it uses the same amount of data whether you cast or watch on your phone. If you are on a cellular connection away from home, you cannot cast to a home Chromecast, so it is not a concern for mobile data.

Can multiple people cast to the same TV at the same time?

Most Chromecast devices queue up casting requests, so only one person can cast at a time. If two people tap Cast simultaneously, one will see a message saying the Chromecast is busy. Some newer Google TV devices allow multiple people to take turns more smoothly, but only one video plays at a time.

What if I do not have a Chromecast—can I still cast?

No. You need a device with a Chromecast receiver to cast to. If your TV does not have Chromecast built in, you can buy a standalone Chromecast device (the small HDMI dongle) or a Chromecast with Google TV (a full streaming box). Some smart TVs from Samsung, LG, and other brands have Chromecast built in—check your TV's manual.

Why does my phone get hot when I screen mirror?

Screen mirroring uses much more of your phone's processor and Wi-Fi radio than casting an app does, which generates heat. If you are screen mirroring for a long time, your phone may throttle (slow down) to cool itself. Casting an app instead of screen mirroring will use less battery and keep your phone cooler.