For streamers
Twitch Vertical Streaming: Dual Format
By Florian Weber · Chief Technology Officer
A growing share of your audience watches you on a phone. Twitch vertical streaming — officially Dual Format — is the answer to that: you broadcast the same show simultaneously as a conventional landscape picture and as a second, purpose-built portrait one. Twitch then decides per viewer which of the two to serve. For you that is not double work during the stream, but one-off work in the setup.
What Dual Format actually is
Your encoder sends two video tracks to Twitch: the familiar 16:9 picture, plus a 9:16 picture that you lay out as its own canvas in your broadcasting software. Common resolutions for the vertical track are 720 × 1280 or 1080 × 1920 pixels. Someone opening your channel on a phone held upright gets the portrait version; on desktop nothing changes.
The crucial point is that portrait is not cropped landscape. Crop your 16:9 picture at the edges and half your face ends up outside the frame, your overlay entirely. The vertical canvas needs its own arrangement: camera large, gameplay above or below it, alerts somewhere that does not cover the middle.
What that means for your setup
Budget one quiet hour without viewers for the first build. The order that works:
- Create a vertical scene. A new portrait canvas, not the old one scaled down.
- Re-place your sources. Set camera, gameplay and chat individually instead of carrying over a group.
- Check it on a phone. Open your own channel on mobile and look at what is actually visible.
- Overlays last. Anything that gets displayed belongs at the edge, not across your face.
The last point is where most setups fail. Landscape gives you room at the sides; portrait does not.
Ads on the vertical canvas
If you run ads through us, you add a second browser source for the portrait canvas. It uses the same token as your existing source, just with the vertical suffix. Once it is set up, it receives the same ad as your landscape canvas, at the same moment and from the same campaign.
Three things are deliberately built this way:
- It does not count as a second impression. Both canvases show the same ad to the same viewers. Billing that twice would simply be wrong.
- The vertical surface costs nothing extra. It changes neither the campaign price nor your payout.
- You choose the position. Top or bottom, depending on where your layout has room.
How the landscape placement works in general is covered in our explainer on in-stream ads. If you have not set up your first browser source at all yet, start with the OBS browser source guide and come back here afterwards.
Is it worth the effort
Honestly: it depends on how many of your viewers are on mobile. Twitch publishes no per-channel figure for that, and we see it no better — we can only tell whether a vertical source is connected, not how many people see it. So anyone streaming portrait regularly should watch it themselves: viewer counts and watch time before and after the switch, across several streams.
What can be said in advance is that the effort is one-off and the surface stays. And a channel that looks right on a phone loses fewer people in the first few seconds — exactly where most viewers decide whether to stay.