Grout Calculator
Installing tile? Find out exactly how much grout you need by entering your tile dimensions and project area. Avoid over-ordering or running short.
Grout Coverage and Joint Size
Grout consumption is driven by joint width, joint depth, and tile size. A 12×12-inch tile with 1/8-inch joints uses far less grout per square foot than a 2×2-inch mosaic with the same joint width, because smaller tiles have proportionally more joint area. This calculator accounts for that relationship by computing the linear feet of joint per tile, then multiplying by joint cross-section and the number of tiles.
Joint depth matters just as much. Wall tile joints are often only as deep as the tile thickness, around 1/4 inch. Floor tile joints may run deeper if the thinset bed is thick or if you're grouting over a membrane. Shallow joints save grout but compromise durability; the grout needs enough depth to lock in mechanically and resist cracking.
A standard 25-pound bag of grout covers roughly 100-200 square feet of 12×12-inch tile with 1/8-inch joints, but coverage drops sharply with smaller tiles or wider joints. Always buy at least one extra bag to ensure color consistency—mid-project batch changes can result in visible shade variations.
Sanded vs. Unsanded Grout
Sanded grout contains fine sand aggregate that adds body and prevents shrinkage in joints wider than 1/8 inch. The sand locks the grout in place and resists cracking under foot traffic. Use sanded grout for most floor tiles and any wall tiles with joints 1/8 inch or wider.
Unsanded grout is pure cement paste with no aggregate. It's designed for joints narrower than 1/8 inch, especially on polished marble, glass, or metal tiles where sand could scratch the surface. Unsanded grout shrinks more than sanded, so it must be applied carefully and not used in wide joints.
Epoxy grout offers a third option: waterproof, stain-proof, and incredibly durable, but it costs three times more than cement grout and sets faster, leaving little room for error. Epoxy is worth it for high-traffic commercial floors, restaurant kitchens, and shower floors where mold and staining are constant concerns. For most residential projects, standard sanded or unsanded cement grout performs well when properly sealed.
Mixing and Application Best Practices
Mix grout to a thick peanut butter consistency. Too wet and it shrinks excessively, cracks, and lightens in color. Too dry and it won't pack into joints or achieve full contact with tile edges. Add water slowly, mix thoroughly, then let the batch slake for 10 minutes before remixing. This hydration period activates the cement and improves workability.
Apply grout with a rubber float held at a 45-degree angle, forcing it diagonally across joints to pack them completely. Work in small sections—about 10 square feet at a time—so you can clean before the grout skins over. Once joints are full, hold the float at 90 degrees and scrape off excess, moving diagonally to avoid pulling grout out of joints.
Wait 15-20 minutes, then sponge the surface with clean water, rinsing the sponge frequently. Don't flood the tiles or you'll weaken the grout. Multiple light passes are better than one heavy scrub. A haze will form as the grout cures; buff it off with a dry microfiber cloth after 24 hours. Avoid foot traffic for at least 24 hours, and don't seal for 48-72 hours to allow full curing.
Frequently Asked Questions
How much grout do I need for 100 square feet of tile?
For 12×12-inch tiles with 1/8-inch joints, you need about 8-10 pounds of grout per 100 square feet. Smaller tiles or wider joints increase grout consumption significantly.
What is the standard grout joint width?
Floor tiles typically use 1/8-inch to 1/4-inch joints. Wall tiles often use 1/16-inch to 1/8-inch joints. Rectified tiles can go tighter, while natural stone may need wider joints to accommodate size variation.
Can I use sanded grout for thin joints?
No. Sanded grout is for joints 1/8 inch and wider. Use unsanded grout for joints narrower than 1/8 inch to prevent scratching polished tile surfaces.
How deep should I fill grout joints?
Fill joints to at least 2/3 the tile thickness. Shallow grout cracks easily and looks unfinished. Most floor tiles sit on a 1/4-inch to 3/8-inch thinset bed, so joints should be at least 1/4 inch deep.
Do I need to seal grout?
Yes, especially for sanded grout in wet areas like showers and kitchen backsplashes. Epoxy grout is pre-sealed but costs more and requires faster work. Cementitious grout should be sealed 48-72 hours after installation and resealed annually.