All of my oak floating shelves, made from white oak, specifically, is made to order between 12" and 72" long and 6" to 12" deep. Here's what I typically recommend based on how people use them:
8" deep works well for lighter display use: picture frames, candles, small plants, or a row of spice jars. It's also the most popular depth for bathroom shelves where wall space is tight.
10" deep is the sweet spot for most rooms. It handles books, mugs, kitchen items, and decor without sticking out too far from the wall. If you're unsure, this is what I'd suggest. I go into more detail in the floating shelf depth guide.
12" deep is the move for kitchen storage, dinner plates, heavy cookware, or anywhere you want maximum usable surface area. At this depth, proper bracket support is critical, which is why every shelf ships with the Hovr bracket rated at 150 pounds per stud.
Need a custom length or depth? Order the closest size and put your exact dimensions in the order notes on the cart page. Need something longer than 72"? Reach out directly.