Steam Custom Image Sizes
Banner: 1920px x 620px PNG, or 3840px x 1240px (for 4k) Grids/Cover Art: These files are 460 x 215 pixels. You can use .PNG, .JPG, or .TGA file types. Icons: 256 x 256 pixels
Banner: 1920px x 620px PNG, or 3840px x 1240px (for 4k) Grids/Cover Art: These files are 460 x 215 pixels. You can use .PNG, .JPG, or .TGA file types. Icons: 256 x 256 pixels