Floor & Wall Tile Calculator

Buying tile is a three-part problem: how many tiles, how much thinset to set them, and how much grout to fill the joints. This calculator handles all three from the room area, the tile size, and your grout joint, and adds a waste factor so you do not run short mid-job.

How it works

tile face area  = (tileW + joint) * (tileH + joint)   [in², includes one joint]
tiles per sq ft = 144 / tile face area
tiles needed    = ceil(area * tiles per sq ft * (1 + waste))
thinset bags    = ceil(area * (1 + waste) / bag coverage)
grout (lb)      ≈ ((tileW + tileH) / (tileW * tileH)) * joint * depth * 0.62 * area

Adding the joint to each tile dimension is the detail people miss — it slightly lowers the tile count and matters on big jobs. The grout estimate scales with joint width, joint depth, and how small the tiles are.

Worked example: 200 sq ft floor with 12 × 12 tiles

• Room area: 200 sq ft
• Tile size: 12 × 12 inches
• Grout joint: 1/4 inch (0.25 in)
• Waste factor: 10%
• Thinset coverage: 45 sq ft per bag
• Grout joint depth: 1/8 inch (0.125 in)

tile face area  = (12 + 0.25) × (12 + 0.25) = 12.25 × 12.25 = 150.06 in²
tiles per sq ft = 144 / 150.06 ≈ 0.9596
tiles needed    = ceil(200 × 0.9596 × 1.10) = ceil(211.1) = 212 tiles
thinset bags    = ceil(200 × 1.10 / 45) = ceil(4.89) = 5 bags

For the grout (illustrative calculation):

grout factor = (12 + 12) / (12 × 12) = 24 / 144 = 0.1667
grout ≈ 0.1667 × 0.25 × 0.125 × 0.62 × 200 ≈ 0.65 lb × 200 ≈ 5.2 lb? 

Real grout coverage depends on manufacturer data. The tool uses the industry-standard formula and your inputs; always round up to the nearest full bag or box since partial amounts are not usable mid-job.

Waste factor guidance

Not all tiling jobs need the same waste allowance. The right factor depends on the layout:

Diagonal layouts generate the most waste because every perimeter cut is an angled cut — you get half of each tile rather than a strip. Keep at least a few tiles from the same dye lot for future repairs; once a dye lot is sold out, the colour match from a later batch is rarely perfect.

Thinset types and coverage

Coverage per bag varies by the thinset product and the notch trowel size:

• 1/4 × 1/4 inch square notch: 40–50 sq ft per 50 lb bag. Suitable for tiles up to about 12 inches.
• 1/4 × 3/8 inch square notch: 30–40 sq ft per bag. For 12–18 inch tiles.
• 1/2 inch square notch: 20–30 sq ft per bag. For large-format tiles (18 inches and above).

Large tiles (18 inches and larger) often require a back-buttering technique in addition to floor coverage, which increases thinset consumption.

Grout joint width conventions

Standard joint width varies by tile type and size:

• Rectified tiles (factory-cut to exact size): 1/16 to 1/8 inch minimum — tight grout lines are possible because the edges are very consistent.
• Non-rectified tiles (natural variation): 1/8 to 3/16 inch to accommodate size differences between tiles.
• Large-format tiles: 3/16 to 1/4 inch minimum for floor, which helps accommodate any minor lippage.
• Mosaic tiles on mesh: Usually pre-determined by the mesh spacing; typically 1/16 to 1/8 inch.

A wider joint increases the amount of grout needed. For a 12 × 12 tile, going from a 1/8 inch to a 1/4 inch joint roughly doubles the grout volume.

Buying tips

• Always buy tiles from a single dye lot (shown on the box). Colours vary between lots.
• Order from one supplier in one purchase — it is much harder to match a second order later.
• Round quantities up to whole boxes; tile is sold by the box (typically 5–15 tiles per box).
• Buy about 10–15% more than the calculation to keep matching spares for future repairs.

All calculations run in your browser — nothing is sent anywhere.