Slot thumbnail sizes and casino lobby tile dimensions
There is no single standard size for a slot thumbnail: every casino platform uses its own grid. What repeats are 6 aspect ratios. This guide lists them with practical pixel sizes, explains where each one is used and how to prepare files so that one master covers the whole lobby.
Slot thumbnail sizes at a glance
| Ratio | Files | Pixel sizes | Where it is used |
|---|---|---|---|
| 2:3 | Files:2 | Pixel sizes:512×768 · 1024×1536 (@2x) | Where it is used:Mobile-first lobby grids, poster-style tiles |
| 3:4 | Files:3 | Pixel sizes:768×1024 · 427×575 · 316×425 | Where it is used:Desktop and tablet grids with shorter tiles |
| 1:1 | Files:3 | Pixel sizes:1024×1024 · 380×380 · 190×190 | Where it is used:Classic grids, search results, recently played, small widgets |
| 9:16 | Files:1 | Pixel sizes:864×1536 | Where it is used:Stories and full-screen mobile placements |
| 16:9 | Files:2 | Pixel sizes:1536×864 · 337×181 | Where it is used:Featured rows, game pages, promo blocks |
| 21:9 | Files:2 | Pixel sizes:1540×660 · 236×110 | Where it is used:Top-of-lobby carousels and desktop strips |
How to choose a size for your lobby
- Measure the rendered tile, not the design mock. Check the largest size at which a tile is actually displayed, in CSS pixels, on desktop and on a phone.
- Double it for retina screens. A tile needs a file twice as wide as its CSS size to stay sharp on a high-density screen; that is why the portrait set includes an @2x file.
- Keep one ratio per row. Mixing portrait shapes in the same row makes the grid look broken; switch the ratio between sections instead.
- Serve the smallest file that is still sharp. Use the small operator sizes in dense lists and widgets.
Safe zones for the title and the studio name
- Keep the game title away from the edges: lobbies round the corners and put badges such as NEW, HOT or JACKPOT in them.
- Keep the hero and the title in the central part of the image, because the same master is cropped into square, wide and ultra-wide shapes.
- The title has to stay readable at the smallest size you ship, so check it on the smallest square icon.
- Prefer a live text layer to text baked into the art: a renamed game or a new market should not mean redrawing the tile.
In Slot Preview AI the caption is that kind of live layer: editing it and the corner radius is free, and it is composited into every exported file exactly as previewed.
File formats: PNG, WebP or AVIF?
Keep a lossless PNG as the source of truth and deliver a compressed format to players. WebP is supported by every current browser and is much lighter than PNG; AVIF is lighter still where your CDN supports it. Slot Preview AI exports PNG by default and can build the same set in WebP, JPEG and AVIF in one purchase through the API.
One master, every file
Redrawing a tile for every ratio is where lobby art gets expensive. A single portrait master contains enough image to produce every format above. Slot Preview AI generates that master with AI and exports all 13 files for 2 tokens.
Questions operators ask
What is the standard size of a slot thumbnail?
There is no single standard. The most common shapes are portrait tiles and square icons; the table above lists the pixel sizes that cover most lobby grids.
What size is a casino game icon?
Square icons are the norm, with a small size for dense lists, a medium one for standard grids and a large one as a high-resolution source. All three are in the table above.
What aspect ratio is best for a mobile casino lobby?
Portrait tiles use the width of a phone screen best, and the vertical story format works for full-screen placements.
Should thumbnails be PNG or WebP?
Keep PNG as the master and serve WebP or AVIF to players to cut page weight.
