In short: Type in the Channels field and pick from the list. Each one gets its own design.
A channel here just means an output size with a name. Instagram Story is one, A4 Portrait is another, and so is the 300×250 banner your media agency keeps asking for.
Start typing
The field autocompletes across the built-in sizes. Type Instagram, LinkedIn, newsletter, landing page or DOOH and the matches appear.
Pick as many as you need
Each selection becomes a chip. Every channel you add produces its own design at its exact dimensions, composed for that shape rather than cropped down from one master.
Add your own size
If the size you need is not there, use Custom format, give it a name and its width and height, and it is saved for your brand and available next time.
Shape changes the composition
A story and a leaderboard are not the same design at different sizes. Sketch recomposes for each, and keeps text clear of the areas platforms cover with their own interface.
More channels means more work generated, so pick the ones you will actually use. You can always add another and regenerate.
Last updated 13 August 2026
