Tile and Grout Calculator
Tile installation requires accurate estimates for tiles, thin-set mortar, and grout. Buying too few tiles risks dye-lot mismatches if you have to reorder; buying too much grout is a common and avoidable waste. This calculator computes the number of tiles needed (area / tile area, plus waste), the mortar (area / coverage per bag), and grout weight using the TCNA formula based on tile dimensions, joint width, and grout depth. Enter all dimensions and joint width in inches.
Tile and grout quantity formulas
Tile area = (tile length + joint width) x (tile width + joint width) / 144 sq ft
Tiles = ceil(Area / Tile area x (1 + waste%))
Grout (lb) = Area x joint width x grout depth x 2 x 144 / (tile length x tile width) / 16
Mortar bags = ceil(Area / 45) (using 45 sq ft per 50-lb bag estimate)
The grout formula calculates the volume of all joints and converts to pounds using an approximate grout density of approximately 100 lb/ft3. Actual grout consumption varies by brand and application. The mortar bag estimate uses a mid-range 45 sq ft per 50-pound bag; verify with the mortar manufacturer's coverage data for your trowel size and tile.
Tile installation guidelines
- Use a minimum 3/16-inch notch trowel for standard floor tiles; 1/2-inch notch for large-format tiles over 15 inches.
- Back-butter large tiles to achieve at least 95 percent mortar coverage on the tile back (TCNA Handbook F125).
- Allow 24 to 48 hours before grouting to give mortar time to cure.
- Use unsanded grout for joints 1/8 inch or less; sanded grout for joints wider than 1/8 inch.
- Seal natural stone and unglazed tiles before grouting to prevent staining.
Tile and grout calculator: frequently asked questions
How do I calculate the number of tiles needed?
Divide the total area by the area of one tile, then add a waste factor. For example, 100 square feet divided by 1 square foot per tile = 100 tiles, plus 10 percent waste = 110 tiles.
How much grout do I need?
Grout quantity depends on tile size, joint width, and grout depth. A common approximation for standard 12x12 tiles with 1/8-inch joints and 3/8-inch depth is about 0.5 to 1 pound of grout per square foot. Check the grout manufacturer's coverage chart for your specific tile and joint size.
What is the standard joint width for floor tiles?
Floor tiles typically use 1/8-inch to 3/16-inch joints. Wall tiles often use 1/16-inch to 1/8-inch joints. Larger format tiles (18x18 or larger) typically need wider joints to accommodate lippage variation.
How much waste should I add for tiles?
Add 10 percent for straight-lay installations. Add 15 percent for diagonal (45-degree) installations. Add 15 to 20 percent for complex patterns or rooms with many cuts, such as L-shaped spaces or rooms with curved walls.
How do I calculate mortar (thin-set) needed?
Thin-set mortar coverage is typically 40 to 50 square feet per 50-pound bag for standard notch trowels with most tile sizes. Large-format tiles require a larger notch trowel, reducing coverage to 30 to 40 square feet per bag.
Official sources
- Tile Council of North America: TCNA Handbook for Ceramic, Glass, and Stone Tile Installation.
- American National Standards Institute: ANSI A108 Tile Installation Standards.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.