Step 1: Sign in to Fotor Graphic Designer and choose a template.
Step 2: Click “Resize” at the top menu, and then choose Custom Size.
Step 3: Fill in the size you want and then click “Resize” button and the canvas size will change. If you want to keep the current design unchanged and create a new one, you can choose "Copy & Resize" and there will be a new window opened with the resized design.