Tile Grout Quantity Calculator
Calculate pounds of grout needed for any tile project from tile size, joint width, and square footage.
Covers sanded and unsanded grout for all tile formats.
What Is Grout and Why Calculate It?
Grout is the material that fills the joints between tiles. It seals the gaps against moisture, dust, and debris while providing a finished, polished appearance. Buying too little means a frustrating mid-project trip to the store, and color batches can vary between purchases. Buying too much wastes money. A precise calculation is always worth the two minutes it takes.
The Grout Coverage Formula
The standard formula used by tile manufacturers is: Pounds of grout = (Tile length + Tile width) ÷ (Tile length × Tile width) × Joint width × Joint depth × 144 × Grout density
Where tile dimensions are in inches, joint width and depth are in inches, 144 converts square inches to square feet, and grout density is approximately 0.092 lbs per cubic inch for sanded grout.
Sanded vs. Unsanded Grout
Unsanded grout is used for joints narrower than 1/8 inch (3 mm). It contains no sand particles, which would scratch delicate tile surfaces like marble or polished ceramic. Sanded grout is used for joints 1/8 inch and wider. The sand particles prevent shrinkage and cracking in wider joints. Using the wrong type causes either cracking (no sand in wide joints) or scratching (sand in narrow joints).
Tile Size and Grout Consumption
Smaller tiles have more joint length per square foot and therefore consume far more grout. A 2×2-inch mosaic tile installation uses roughly 4× more grout than a 12×12-inch tile installation over the same area. Large-format tiles (18×18 inches and above) use very little grout per square foot.
Grout Joint Depth
Joint depth is typically the thickness of the tile itself for floor tiles, or 2/3 of the tile thickness for wall tiles. Standard ceramic tiles are 3/8 inch thick; porcelain tiles are often 1/2 inch thick. This calculator assumes a joint depth of 80% of the input you provide (accounting for the tile adhesive below filling part of the void).
Waste Allowance
Always purchase 10–15% extra grout. Mixing losses, joint overfill, and the fact that opened bags cannot be returned means running short is a real risk.