The thickness of the cement bed for floor tiles can vary depending on several factors, including the type and size of the tiles, the condition of the subfloor, and the specific requirements of the project. In general, however, a common range for the thickness of the cement bed or mortar bed is typically between 1/4 inch (6 mm) and 1 inch (25 mm).
Smaller tiles, such as mosaic or subway tiles, may require a thinner bed of around 1/4 to 3/8 inch (6 to 9 mm). Larger tiles, such as porcelain or ceramic tiles, often necessitate a thicker bed to ensure proper support and prevent cracking, which can range from 3/8 to 3/4 inch (9 to 19 mm) or even up to 1 inch (25 mm) in some cases.
It's important to note that these measurements are approximate and can be influenced by specific circumstances. It's always recommended to consult the manufacturer's guidelines and follow the recommendations of a professional tile installer or contractor to determine the appropriate thickness for your specific project.