Tile Calculator
Work out tiles and boxes needed with waste allowance, plus grout estimate.
Inputs
Found on the tile box label.
10% for straight lay, 15% diagonal, 20% for complex patterns.
⅛ in (0.125) is standard for most floor tiles.
Typically ⅜ in (0.375 in) for standard ceramic tile.
Tiles Needed
132
Rounded up, includes waste.
Boxes Needed
14
Rounded up.
Room Area
120.00sq ft
Area per Tile
1.0000sq ft
Grout Needed
1.5lb
Step by step
Room area
12 ft × 10 ft
= 120.00 sq ft
Area per tile
(12 in ÷ 12) × (12 in ÷ 12)
= 1.0000 sq ft
Tiles required (net)
120.00 ÷ 1.0000
= 120.0 tiles
Add 10% waste
120.0 × 1.10
= 132.0 → 132 tiles
Boxes
⌈132 ÷ 10⌉
= 14 boxes
Grout estimate
(12+12)/(12×12) × 0.125 × 0.375 × 1.44 × 120.0 sq ft
= 1.48 lb
How it works
Tiles required equals the room area divided by the area of one tile, rounded up. A waste factor covers cuts and breakage — 10% for a straight lay, 15% for a 45° diagonal, up to 20% for complex patterns. Boxes are rounded up to the nearest whole box. Grout consumption is estimated with the formula (W + H)/(W × H) × joint_width × tile_depth × 1.44, which derives from the volume of the grout joints and a density factor for Portland-cement-based grout.
Formulas
Tiles required
Tiles = ceiling(room_area ÷ tile_area × (1 + waste%))
Grout (lb/sq ft)
Grout lb/sq ft = (tile_length + tile_width) / (tile_length × tile_width) × joint × depth × 1.44
- T_L
- Tile length (in)
- T_W
- Tile width (in)
- J
- Joint width (in)
- D
- Tile depth (in)
Frequently Asked Questions
Why should I add waste to my tile count?
Tiles need to be cut at walls, corners and obstacles. Some tiles crack during installation. 10% waste is a safe minimum for simple straight-lay floors. Increase to 15–20% for diagonal or complex patterns where cuts waste more material.
How do I find 'tiles per box'?
Check the tile carton label — it lists how many tiles and the coverage area. Enter that number in the 'Tiles per Box' field.
How accurate is the grout estimate?
The formula gives a good approximation for standard Portland-cement grout. Epoxy grouts and specialty mixes have different densities. Check the manufacturer's yield chart for precision.
Does this work for wall tiles?
Yes — measure the wall area (height × width) as you would a floor, and the calculation is identical.