# Flooring and tile calculator

> Tile calculator: tiles and boxes for a floor or wall from room size, tile size, grout joint and waste allowance, plus grout in litres and kg.

Versão interativa: https://www.calcopenly.com/pt/construction/tile-calculator
Tema: Calculadoras de construção e casa

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.

## Dados

- **Area length**
- **Area width**
- **Tile length**
- **Tile width**
- **Grout joint**
- **Tile thickness (joint depth)**
- **Waste allowance**: Covers cuts and breakage. Diagonal and herringbone layouts cut more tiles at the edges.
- **Tiles per box**
- **Price per box**

## Resultados

- Tiles to buy (tiles) — resultado principal
- Boxes to buy (boxes)
- Área (m²)
- Área (ft²)
- Grout volume (L)
- Grout (dry weight) (kg)
- Tile cost

## Fórmula

$$
N = \left\lceil \frac{A}{(\ell_t + j)(w_t + j)} \times (1 + \text{waste}) \right\rceil,\qquad G = \frac{\ell_t + w_t}{\ell_t w_t} \cdot t \cdot j \cdot A
$$

## Exemplos resolvidos

### 4 × 3 m floor, 600 × 300 mm tiles, 3 mm joints, 10% waste

- Area length: 4 m
- Area width: 3 m
- Tile length: 600 mm
- Tile width: 300 mm
- Grout joint: 3 mm
- Waste allowance: 10%
- Tiles per box: 8
- **Área: 12 m²**
- **Tiles to buy: 73 tiles**
- **Boxes to buy: 10 boxes**
- **Grout volume: 1.62 L**
- **Grout (dry weight): 2.59 kg**
- **Tile cost: 400.00**
- Fonte de verificação: 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

### 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.

## Fontes

- [Mapei grout calculator — consumption (A + B)/(A × B) × C × D × 1.6 = kg/m²](https://www.mapei.com/gb/en/tools-and-downloads/product-calculator/grouts)
- TCNA Handbook for Ceramic, Glass, and Stone Tile Installation — joint widths and layouts