How many 12×12 tiles do I need for 100 sq ft?

With standard 1/8 in joints, each tile covers 147.02 sq in once laid, so 100 sq ft needs 98 tiles before waste and 108 with a 10% allowance. Enter your area and tile size above for the exact figure with your grout gap.

Does the grout gap really change the tile count?

Yes, by a few percent. The joint is dead space the tile does not cover, so wider joints mean each tile accounts for more floor. On a large floor the difference between a 1/16 in and a 1/4 in joint can be a full box.

How much waste should I add for tile?

Add 10% for straight layouts in simple rooms and 15% for diagonal layouts, small bathrooms with many cuts, or brittle porcelain and natural stone. Keep the leftovers — a discontinued tile cannot be matched later.

How do I count mosaic tiles?

Treat each mesh sheet as one tile and enter the sheet dimensions (commonly 12 × 12 in). The calculator then counts sheets and boxes the same way, and the grout gap is the joint between sheets.

Should I buy one extra box even if the count looks exact?

Yes. Tile breaks in transit and during cutting, and dye lots vary between production runs. One spare box bought with the original order is cheap insurance against a visible shade mismatch later.

Tile Calculator — Free, With Formula & Worked Example

About this calculator

Tile quantities depend on both the area and the tile format: a 24×24 in tile covers four times the area of a 12×12 in tile, and grout joints shrink the effective coverage slightly. This calculator counts individual tiles and boxes, with a waste allowance for cuts and breakages.

What this number means

Tile is the material where "area ÷ tile area" goes wrong most often, because the grout joint is part of every tile's footprint once laid. A nominal 12×12 in tile with a 1/8 in joint actually occupies 12.125 × 12.125 in of floor — about 2% more than its face — and across a whole room that difference is several tiles.

The calculator counts in two steps: the exact tile count your layout needs including cuts and breakages (the waste allowance), then the boxes that count converts into, since tile is bought by the box.

The formula

Tile pitch = (Tile width + grout gap) × (Tile length + grout gap), in square inches
Tiles = Surface area (sq in) × (1 + waste %) ÷ tile pitch, rounded up
Boxes = Tiles ÷ tiles per box, rounded up

Surface dimensions are converted to inches first (feet × 12, metres × 39.3701).

Worked example

A bathroom floor in 12×12 tile. The floor is 5 ft × 8 ft, joints are 1/8 in, and 10% waste covers the cuts around the tub and door.

Surface area = 40 sq ft = 5,760 sq in
Tile pitch = 12.125 × 12.125 = 147.02 sq in per tile once laid
Tiles = 5,760 × 1.10 ÷ 147.02 = 43.1 → 44 tiles
At 10 tiles per box: 5 boxes

Assumptions and limitations

The count assumes a straight grid layout aligned to the room. Diagonal (45°) layouts genuinely need 15% waste; running-bond patterns sit between the two.
Border tiles, feature strips and different-format accent tiles must be calculated as their own surfaces.
Nominal tile sizes are used as entered. Some "12 inch" tiles are actually 11.75 in — if your tile is sold by a metric size (600 × 600 mm), enter 23.6 in.
Grout, thinset and backer board are separate calculations — see the Grout Calculator for joint material.