Tile Grout Calculator

Measured area (sq ft). Enter the tiled surface whose joints will be grouted. Calculate separate tile sizes or joint arrangements separately. The estimate treats the surface as a repeating rectangular tile grid and does not measure unusual edge or decorative joints individually.

Tile face length (in). Measure the actual face length of one tile, excluding the joint. Nominal tile size may differ from the finished face. The joint width is added separately when determining how much of the tiled surface consists of joints.

Tile face width (in). Measure the other face dimension of the same tile, without grout. Smaller tiles generally create more joint length within the same area. Mixed-size or irregular tiles need a more specific coverage estimate.

Joint width (in). Measure the clear gap between adjacent tile faces that will receive grout. Use the intended installed joint rather than adding it to the tile dimensions above. The same joint width is used in both directions.

Filled grout depth (in). Enter the depth of the joint actually filled with grout. Mortar beneath the joint, edge profiles and installation details can make this different from the full tile thickness. A deeper filled joint requires more grout.

Dry product yield density (lb per cu ft). This figure is the dry product weight needed to produce one cubic foot of installed grout. Obtain it from manufacturer yield information or technical support for the chosen product. Wet grout density or mixing-water weight is not a substitute; if this conversion is unavailable, use the manufacturer’s coverage calculator to confirm purchasing.

Dry grout per bag (lb). Enter the dry grout weight supplied in one bag or package. Use the package size for the same product as the yield figure. Mixing water is not part of this dry purchasing quantity.

Allowance (%). Enter the percentage you want to add for cutting, handling loss or other conditions specific to this work. Apply it to the measured quantity rather than enlarging the measurements as well. The suggested value is editable, not a universal recommendation; enter zero when no allowance is needed.

Joint volume estimates the space filled by grout, with crossings counted once. Required dry weight converts that volume using your product yield and includes the allowance; bags round the dry weight upward to complete packages. Confirm the result with the manufacturer’s coverage information, especially for unusual tile or joint profiles.

Joint area fraction = 1 − (tile length × width) ÷ ((length + joint) × (width + joint)). Volume = surface area × joint fraction × filled depth ÷ 12. Weight = volume × dry-product yield density × allowance factor. Bags = ceil(weight ÷ bag weight).

Worked example: 100 sq ft of 11.75 × 11.75 in tile, 0.25 in joints and 0.25 in filled depth has about 0.0859 cu ft of joint volume. At an illustrative 100 dry lb/cu ft and 10% allowance, allow about 9.45 lb: one 10 lb bag.

Repeating rectangular tile-grid approximation, with joint intersections counted once. Outer edges and irregular tiles are not included. Product yield varies; use manufacturer grout coverage to confirm. Dry-mass-per-installed-volume is not the same as wet grout density. No universal density is assumed.

Reference guidance

MAPEI grout coverage calculator and job-condition guidance. Consult the relevant product or estimating instructions. The illustrative numbers above are not specifications for the linked products.