The size of mosaic tile display panels can vary significantly depending on several factors, including the type of mosaic tiles, the intended display area, and the design preferences of the showroom or retailer. However, there isn't a standard size for mosaic tile display panels due to the diverse range of mosaic tile dimensions and patterns available in the market.

Mosaic tile display panels are typically designed to showcase a variety of tile designs, colors, and patterns. Some common sizes for these panels might include:

1. **Small Panels:** These can range from approximately 12 inches by 12 inches (30 cm by 30 cm) to 18 inches by 18 inches (45 cm by 45 cm). These smaller panels might display individual tile patterns or small sections of mosaic designs.

2. **Medium Panels:** Medium-sized display panels could be around 24 inches by 24 inches (60 cm by 60 cm) or slightly larger. These panels might feature larger sections of mosaic patterns or a combination of multiple smaller patterns.

3. **Large Panels:** Larger display panels can exceed 36 inches by 36 inches (90 cm by 90 cm) or more. These panels might showcase larger sections of intricate mosaic designs or a variety of mosaic tile arrangements.

It's important to note that mosaic tiles are often sold in sheets or mesh-mounted configurations, where individual tiles are mounted on a backing material. Display panels may vary in size to accommodate these sheet-mounted tiles or individual patterns, allowing for a visually appealing and comprehensive display of mosaic tile options.

Ultimately, the size of mosaic tile display panels can be tailored to the specific needs of the showroom, retailer, or the intended display area, ensuring that they effectively showcase the diversity and beauty of mosaic tile designs.