I am not a tile pro but I do know that we use a tile adhesive made for large format tiles for anything larger than the 12 x 24s. The weight of those tiles can be tricky when moving and positioning.

There are a lot of great tile specialists here - give it a bit and they will chime in!

12 X 24 is a popular size. If I were you I would stick with what you're comfortable working with. What is leading you to think you should be using 24 X 24 instead?

@hgtvisfiction: "Even 12x24 verges on too large for a room that size."

Why? The space would be roughly 4 tiles long and 8 tiles wide (ignoring closet). Why would 12x24 tiles be too large? An 8' x 9' space would require her to lay about 36 12x24 tiles. The same space would require a whopping 158 8x8 tiles.*

*Title calculator

kandrewspa - I'm going for an industrial look and wanted concrete porcelain tiles. I thought the larger tile size would be more appropriate for the concrete industrial look.

Emser and EmilAmerica have a selection of concrete-look tile. The Emil Ceramica Be-Square Catalog and Totalook Catalogs contain all sorts of ideas on how the floor tiles can be combined with wall tiles on shower walls and other vertical surfaces. Not all products are available 12x24.

You say you are confident laying 12" by 24" tile. What do you mean by that really? What sort of projects have you done? Are you experienced in cutting tile? Porcelain tile is harder to cut than ceramic, and you will need a diamond tipped bit to drill into porcelain. Bigger tile is going to be more difficult to cut than smaller tile in general. What are your expectations for the room? Are you talking just doing the floor or are you talking about doing the walls too? These are rhetorical questions.

Small tiled bathrooms can be a pistol, particularly around toilets. If you are expecting perfection and have limited experience, I think you are going to be disappointed, especially if your floors are less than perfectly level. It isn't just the manual skill of buttering a tile and sticking it on the floor that matters. A good tiler knows where to start in a room, how to lay the tile out to fit the size of the room, how to tile around elements in the room, and how to lay out the tile based on the tile's pattern. If you don't want to spend the money on a tiler, you feel you are good enough, and/or can live with your imperfections, then go for it.

From a design perspective, I did my 5' x 9' bathroom in 18" tile on the floor and 21" tile on the walls and ceiling (entire room is tiled). I did not do it myself. I was nervous about using larger tile in a small bathroom, but the sizes of the tile looked great in the room.

I like 12 x24 tile IMO a bit more modern looking Ialso like to lay them stacked and us ethe same porcealai tile for the bathroom floor and shower walls and layed in the same direction so they look like they just contiued up the walls Figuring out how to get them properly layed out is best done on pper with to scale drwaing of both the space and the tile not very complicated at all. staggering 12 x24 is not good ay 50% so I find the 33% too busy . I also like matching grout .IMO large tiles make space feel larger almost always

@Patricia Colwell Consulting: "I like 12 x24 tile IMO a bit more modern looking also like to lay them stacked and use the same porcelain tile for the bathroom floor and shower walls and laid in the same direction so they look like they just continued up the walls..."

That's what I did though I used a contrasting tile for the long, rear wall of the shower. It was obvious to run full-size tiles along a long wall and bury the cut-to-fit tiles beneath wall-hung vanities.