Cast sends video or audio from your phone, tablet, or computer to a TV or speaker without a cable

When you cast, you're telling your device to send what's on its screen—or just the audio—to another device on the same Wi-Fi network. Your phone doesn't connect directly to the TV with a cable. Instead, both devices talk to your Wi-Fi router, and your phone instructs the TV or speaker to play the content. The TV or speaker does the actual work of playing the video or audio, not your phone.

This is different from mirroring, where your phone's entire screen appears on the TV. When you cast, you're usually sending just one app or video, and your phone can do other things while it's casting. You can check email, take a call, or even turn your phone's screen off—the content keeps playing on the TV.

Key Takeaways

  • Cast works by sending instructions from your phone to a TV or speaker over Wi-Fi, not by plugging in a cable or mirroring your entire screen.
  • Both devices must be on the same Wi-Fi network, and the TV or speaker must have a Chromecast device or built-in cast capability.
  • You control what plays using the cast button in apps like YouTube, Netflix, or Spotify—the TV or speaker does the actual playback.
  • Your phone can be locked or used for other tasks while content is casting, because the TV is streaming directly from the internet.

What you need for cast to work

Your TV needs either a Chromecast device plugged into an HDMI port, or a TV with built-in Chromecast (many newer TVs have this). A Chromecast is a small device about the size of a thumb drive that connects to your TV's HDMI input and to power. Once plugged in, it joins your Wi-Fi network and waits for your phone to send it content.

Your phone, tablet, or computer must be on the same Wi-Fi network as the Chromecast device. If your phone is on your home Wi-Fi and the Chromecast is on a guest network, they won't see each other. Most home Wi-Fi networks are a single network, so this usually isn't a problem—but if you have a separate guest network, make sure both devices are on the main one.

The app you're using—YouTube, Netflix, Spotify, Google Photos—must support cast. Not every app does. If you open an app and don't see a cast button (usually a rectangle with a Wi-Fi symbol in the corner), that app doesn't support it. Many popular apps do: YouTube, Netflix, Disney+, Spotify, Hulu, and Google Photos all support cast.

How the cast button works

When you open a supported app and tap the cast button, your phone searches for Chromecast devices on your Wi-Fi network. A list appears showing the name of your TV or speaker. You tap the one you want, and your phone sends the app a command: "Play this video on that device."

The app then tells the Chromecast device to fetch the video or audio directly from the internet. Your phone doesn't send the video itself—it just sends the instructions. The Chromecast downloads the content and plays it. This is why your phone can be locked or put away; it's no longer involved in the playback.

To stop casting, you tap the cast button again and select "Stop casting" or "Disconnect." The Chromecast stops playing, and the app on your phone returns to normal.

Why cast uses less battery than mirroring

When you mirror your phone's screen, your phone has to encode everything on its display and send it constantly to the TV over Wi-Fi. This is demanding work and drains your battery quickly. Casting is lighter because your phone only sends a small instruction—essentially a link and a play command—and then steps out of the way.

The Chromecast device handles all the heavy lifting: downloading the video, decoding it, and displaying it. Your phone can even go to sleep. This is why you can cast a movie and then use your phone for something else without the video stuttering or stopping.

What happens if your Wi-Fi drops during casting

If your Wi-Fi connection fails while you're casting, the Chromecast will stop playing after a few seconds. Your phone and the TV have lost contact, so the TV can't receive new instructions and can't read more of the video. When your Wi-Fi comes back, you'll need to cast again from the beginning (or from where you paused, depending on the app).

The Chromecast itself doesn't need a strong signal—it just needs to stay connected to your router. If your phone loses Wi-Fi but the Chromecast stays connected, the Chromecast will keep playing until it runs out of buffered video. Once the buffer is empty, it stops.

Casting audio to speakers

Cast works the same way with speakers that have built-in Chromecast or with a Chromecast Audio device (though Chromecast Audio was discontinued and is no longer sold). Apps like Spotify, YouTube Music, and Google Podcasts let you cast audio to a speaker in another room. You tap the cast button, select the speaker, and the audio plays there instead of on your phone.

This is useful for playing music in your kitchen while you're cooking, or in your bedroom while you're getting ready. Like video casting, your phone can be locked or used for other things while the audio plays.

Casting from a computer or tablet

You can cast from a Windows or Mac computer using the Chrome browser. Open a supported website (like YouTube), click the cast button, and select your TV. You can also cast from an Android tablet the same way you cast from a phone. iPads and iPhones don't have a native cast button in most apps, though some apps (like YouTube) do support it.

If you're using an iPad or iPhone and want to send video to a TV, you'll usually use AirPlay instead, which works with Apple TV devices. AirPlay is Apple's version of cast and works on the same principle—your device sends instructions to the TV over Wi-Fi.

Frequently Asked Questions

Can I cast if my phone and TV are on different Wi-Fi networks?

No. Both devices must be on the same Wi-Fi network to communicate. If you're at a hotel or office with a guest network, make sure both your phone and the Chromecast are connected to the same network name.

Does casting use a lot of data?

Casting uses the same amount of data as streaming directly on your TV would use. If you're on a home Wi-Fi network, it doesn't count against a mobile data limit. If you cast over mobile hotspot, it will use your phone's data allowance.

Why doesn't the cast button appear in my app?

The app may not support cast, or your phone and Chromecast may not be on the same Wi-Fi network. Check that both devices are connected to the same network name. If they are and the button still doesn't appear, the app doesn't support cast.

Can I cast to multiple TVs at the same time?

Most apps only let you cast to one device at a time. Some apps and services (like Google Home) let you set up speaker groups so audio plays on multiple speakers, but video casting is typically one-to-one.

What if my Chromecast keeps disconnecting?

This usually means your Wi-Fi signal is weak where the Chromecast is located, or your router is overloaded. Try moving the Chromecast closer to your router, or restart both your router and the Chromecast by unplugging them for 30 seconds and plugging them back in.