Twitch banner size
Your avatar sits over the lower left.
Cropped in your browser · your image is never uploaded
A Twitch profile banner is 1200 × 480 and the offline video banner is 1920 × 1080 — two entirely different placements that people frequently mix up.
How to use the twitch banner size
The offline banner is the one that earns its keep. It is what shows in the player when you are not live, which is most of the time, so it is the first thing a visitor sees — and it is a full 16:9 frame, unlike the narrow 1200 × 480 profile strip. Use it for a schedule and where else to find you. On the profile banner, keep the lower left clear because your avatar sits over it. Panels are a separate 320 × 300 with a tighter file limit, and they stack in a column under the player.
Questions
The profile banner is 1200 × 480; the offline video player banner is 1920 × 1080.