How to Calculate Grout
Grout quantity depends on tile size, tile thickness, joint width, and total area. Smaller tiles with wider joints need significantly more grout than large tiles with thin joints. The formula considers the joint volume per square foot of tile. As a rough guide, 25 lbs of unsanded grout covers about 200 sq ft of 12×12 tile with 1/8-inch joints.
Sanded vs Unsanded Grout
Use unsanded grout for joints 1/8 inch or narrower — it's smoother and works well with polished tile. Use sanded grout for joints wider than 1/8 inch — the sand adds strength and prevents cracking. Epoxy grout is the most durable and stain-resistant but costs more and is harder to apply.