12 m² takes about 65.7 tiles laid edge to edge; with 10% for cuts and breakage buy 73 tiles, which is 10 boxes of 8. The joints need about 2.6 kg of grout.
Tile layout, straight lay (tile size in mm)
Como é calculado S
Área
A=4×3=12m2
Area one tile covers, including its joint
(600+3)(300+3)mm2=0.182709m2
Tiles with waste
0.18270912×(1+0.1)=72.246031⇒73
Rounded up to whole tiles.
Boxes
⌈873⌉=10
Rounded up to whole boxes.
Grout (Mapei consumption formula)
600×300600+300×9×3×12=1.62L×1.6=2.592kg
Lengths in mm give litres of joint per m². 1.6 kg/L is Mapei's factor for cementitious grout; the estimate has no waste added.
Sobre Flooring and tile calculator
The tile count is the area divided by the area one tile covers with its grout joint, (tile length + joint) × (tile width + joint). A waste allowance for cuts and breakage is added, then the count is rounded up to whole tiles and whole boxes. Grout volume per m² is (A + B) ÷ (A × B) × tile thickness × joint width, with A and B the tile sides and all four in millimetres.
The default 4 × 3 m floor in 600 × 300 mm tiles with 3 mm joints takes 65.7 tiles laid edge to edge. With 10% waste that is 73 tiles, or 10 boxes of 8, plus 1.62 L of grout (2.6 kg).
The waste presets are this calculator's rules of thumb: 10% for a straight lay, 15% for diagonal and 20% for herringbone, which cut more tiles at the edges. The drawing shows a straight lay.
Exemplos resolvidos
4 × 3 m floor, 600 × 300 mm tiles, 3 mm joints, 10% waste
12 × 10 ft, 12 in tiles, ⅛ in joints, diagonal 15%
Area length
12 ft
Area width
10 ft
Tile length
12 in
Tile width
12 in
Grout joint
0.125 in
Tile thickness (joint depth)
0.375 in
Waste allowance
15%
Tiles per box
10
Área
120 ft²
Tiles to buy
136 tiles
Boxes to buy
14 boxes
Grout volume
2.21 L
Fonte de verificação: Python decimal: 120 ft² ÷ (12.125 in)² = 117.54 × 1.15 = 135.17 → 136 tiles → 14 boxes of 10; Mapei grout formula in mm
Edge: tiles fit exactly, no joint, no waste
Area length
3 m
Area width
3 m
Tile length
300 mm
Tile width
300 mm
Grout joint
0 mm
Waste allowance
0%
Tiles per box
10
Tiles to buy
100 tiles
Boxes to buy
10 boxes
Grout volume
0 L
Fonte de verificação: Hand calculation: 3 m ÷ 0.3 m = 10 tiles each way = 100 tiles, 10 boxes; a zero-width joint needs no grout
Perguntas
How many tiles do I need per square metre?
Divide 1 m² by the area of one tile plus its joint. A 600 × 300 mm tile with a 3 mm joint covers 0.603 × 0.303 = 0.1827 m², so 1 m² takes 5.47 tiles; 300 × 300 mm tiles take 10.89. Multiply by the whole area before rounding up: rounding 5.47 up to 6 per m² would overbuy by about 10%.
How many tiles do I need for 100 square feet?
About 98 twelve-inch tiles before waste. A 12 × 12 in tile with a ⅛ in joint covers 12.125 × 12.125 in, or 1.021 ft², so 100 ft² takes 97.95 tiles. Adding 10% for cuts and breakage gives 107.7, rounded up to 108 tiles.
How much extra tile should I buy for waste?
This calculator's presets add 10% for a straight lay, 15% for a diagonal lay and 20% for herringbone, because angled layouts cut more tiles along every wall. On the default 12 m² floor those give 73, 76 and 79 tiles of 600 × 300 mm.
How much grout do I need?
Multiply (A + B) ÷ (A × B) by tile thickness and joint width, all in mm, to get litres of joint per m². For 600 × 300 mm tiles 9 mm thick with 3 mm joints that is 900 ÷ 180,000 × 9 × 3 = 0.135 L per m², or 1.62 L for 12 m². The calculator converts at 1.6 kg per litre; check the grout bag's own coverage table.
Do grout joints change the number of tiles needed?
Yes, they lower it slightly, because each tile plus its joint covers more floor. A 600 × 300 mm tile covers 0.18 m² on its own and 0.1827 m² with a 3 mm joint, so 12 m² needs 65.7 tiles instead of 66.7 before waste. For 50 × 50 mm mosaic with 3 mm joints, each tile's footprint grows by 12.4%.
Qual é a precisão de “Flooring and tile calculator”?
A precisão depende dos dados inseridos e das hipóteses do método. O cálculo decimal usa 50 algarismos significativos, mas estimativas, métodos numéricos e dados de origem podem ter menor precisão; o arredondamento exibido não elimina essas limitações. Exemplos resolvidos verificados com fontes independentes: 3. Por exemplo, “4 × 3 m floor, 600 × 300 mm tiles, 3 mm joints, 10% waste” é verificado com Python decimal: 12 ÷ (0.603 × 0.303) = 65.68 × 1.1 = 72.25 → 73; grout (900/180000) × 9 × 3 × 12 = 1.62 L × 1.6 kg/L (Mapei formula); 10 boxes × 40 = 400.
De onde vem o método?
Mapei grout calculator — consumption (A + B)/(A × B) × C × D × 1.6 = kg/m²; TCNA Handbook for Ceramic, Glass, and Stone Tile Installation — joint widths and layouts.
TCNA Handbook for Ceramic, Glass, and Stone Tile Installation — joint widths and layouts
Verificado com as referências
Esta calculadora inclui 3 exemplos resolvidos com respostas de fontes independentes. Eles fazem parte do conjunto de testes e você também pode executá-los aqui.