How do I calculate how many tiles I need?

Tiles needed = Room area / Tile area, then add your waste percentage. Formula: • Room area (m²) = Length (m) × Width (m) • Tile area (m²) = Tile length (m) × Tile width (m) • Tiles net = Room area / Tile area • Tiles to order = Tiles net × (1 + waste % / 100), rounded up Example — 4m × 3m room, 600×600mm tiles, 10% waste: • Room area: 12 m² • Tile area: 0.6 × 0.6 = 0.36 m² • Tiles net: 12 / 0.36 = 33.3 tiles • With 10% waste: 33.3 × 1.10 = 36.7 → order 37 tiles • At 6 tiles/box: 37 / 6 = 6.17 → order 7 boxes

How much grout do I need?

Grout quantity depends on tile size, grout joint width, and tile thickness: Formula: kg/m² = 1.8 × joint width (mm) × tile depth (mm) × (L + W) / (L × W) Common values: • 300×300mm, 3mm joint, 10mm thick: ~0.36 kg/m² • 600×600mm, 2mm joint, 10mm thick: ~0.12 kg/m² • 300×600mm, 3mm joint, 10mm thick: ~0.27 kg/m² Always buy one extra bag — grout is inexpensive and running short mid-job causes colour variation problems if a new batch has a slightly different shade.

How much tile adhesive do I need?

Adhesive coverage depends on the substrate, tile type, and application: • Wall tiles (ceramic, smaller format): 1.5–3 kg/m² • Floor tiles (porcelain, standard): 4–5 kg/m² • Large format tiles (600mm+): 5–7 kg/m² (full bed required) • Natural stone: 4–6 kg/m² This calculator uses 5 kg/m² for floors and 3 kg/m² for walls as conservative defaults. Always check the adhesive manufacturer's coverage rate on the product bag — it varies by tile type and trowel size. 20 kg bag of adhesive covers: • Floor tiles at 5 kg/m²: ~4 m² • Wall tiles at 3 kg/m²: ~6.7 m²

What waste percentage should I use for tiles?

Tile waste allowance by layout type: • 5%: Perfect rectangle, straight grid, all cuts usable • 10%: Standard straight grid — recommended for most rooms • 12–15%: Diagonal (45°) layout — more corner cuts wasted • 15%: L-shaped or irregular room • 15–20%: Herringbone or chevron pattern • 20%+: Natural stone with colour matching, random irregular shapes Never use less than 10% even for simple rooms. Tiles from different batches can have slight colour/shade differences — always buy enough from the same batch. Offcuts from initial installation are also needed for future repairs.

How many tiles come in a box?

Tiles per box varies by manufacturer and tile size: • Small tiles (up to 200×200mm): 16–25 per box, ~1m² per box • Medium tiles (300×300mm, 300×600mm): 6–12 per box, ~1–2m² per box • Large tiles (600×600mm): 3–4 per box, ~1–1.5m² per box • Large format (600×1200mm): 1–2 per box, ~0.7–1.4m² per box The box label always states: tiles per box, square metres per box, and batch/shade number. Always buy all tiles from the same batch (shade lot) — different production runs can have slight colour variations.

What is the difference between floor and wall tiles?

Key differences: • Hardness: Floor tiles have a PEI (Porcelain Enamel Institute) hardness rating of 3–5 suitable for foot traffic. Wall tiles are typically PEI 0–2 — they would crack if used on floors. • Size: Wall tiles tend to be lighter and thinner (6–8mm). Floor tiles are thicker (8–12mm) to handle loads. • Finish: Wall tiles often have a high-gloss finish. Floor tiles are usually matte or textured to prevent slipping. • Adhesive: Floor tiles need a stronger, thicker bed of adhesive. Using wall tile adhesive on floors can cause tiles to crack over time. • Can floor tiles be used on walls? Yes. Floor tiles are generally harder and heavier than wall tiles and will hold fine on walls with the right adhesive. • Can wall tiles be used on floors? No — they are not rated for foot traffic load and will crack.

Tile Calculator — How Many Tiles Do You Need?

The Tile Calculator works out exactly how many tiles to buy for any floor or wall. Enter your room dimensions in metres or feet, select your tile size from common presets (100×100mm through 600×1200mm) or enter a custom size, and the calculator instantly outputs tiles needed with your chosen waste allowance, grout quan..

FLOOR DIMENSIONS

ROOM LENGTH (metres)

ROOM WIDTH (metres)

TILE SIZE — quick presets

LENGTH (mm)

WIDTH (mm)

0.3600 m² per tile · 2.8 tiles/m²

GROUT JOINT (mm)

WASTE (%)

TILES PER BOX (optional)

PRICE PER BOX (optional)

RESULTS

TILES NEEDED (incl. 10% waste)

tiles

GROUT

2.2 kg

1 × 5kg bags

ADHESIVE

60 kg

3 × 20kg bags

TILE LAYOUT PREVIEW — 600×600mm · 3mm joint

MATERIALS SUMMARY

Room area12.00 m²

Tile size600 × 600 mm (0.3600 m²/tile)

Tiles (net, no waste)34

Tiles +10% waste37 ← order this

Grout (3mm joint)2.16 kg (1 × 5 kg bags)

Adhesive (floor)60.0 kg (3 × 20 kg bags)

WASTE GUIDE

Perfect rectangular room, no cuts

10%

Standard — recommended default

15%

Diagonal pattern or L-shaped room

20%

Herringbone, complex layout, stone

GROUT JOINT GUIDE

1.5–2mm

Rectified tiles, tight fit

3mm

Standard wall tiles

4–5mm

Floor tiles, textured tiles

6–10mm

Rustic / handmade tiles

Created with❤️byeaglecalculator.com

HOW TO USE

1
Choose Metric (metres and millimetres) or Imperial (feet and inches), then select Floor or Wall. The application affects the adhesive coverage calculation — floor tiles require more adhesive than wall tiles due to their weight and the bed thickness needed.
2
Enter your room or wall length and width. For an L-shaped room, calculate each rectangle separately and add the tile counts. For walls, measure height × width for each wall section and add them together.
3
Select your tile size using the preset buttons (common sizes from 100×100mm to 600×1200mm are pre-filled), or type custom dimensions in mm directly. The calculator shows tiles per square metre for your selected size.
4
Set your grout joint width. Rectified tiles (machine-cut to exact size) can use 1.5–2mm joints. Standard tiles use 3mm. Natural stone and handmade tiles typically need 5–10mm joints. A larger joint means less grout surface but a different aesthetic. If you know your tile box count and price per box, enter them for a cost estimate.
5
Select your waste allowance: 10% is standard for a simple rectangular room in a straight grid pattern. Use 15% for diagonal layouts or L-shaped rooms, and 20% for herringbone, chevron, or natural stone with irregular sizing. Read your results: tiles needed, boxes to buy, grout quantity in kg and bags, adhesive quantity, and total tile cost.

WORKED EXAMPLE

How many 300×600mm tiles for a 4m × 5m bathroom floor, 10% waste? Step 1: Room area 4m × 5m = 20 m² Step 2: Tile area 0.3m × 0.6m = 0.18 m² per tile Step 3: Tiles needed (net) 20 / 0.18 = 111.1 tiles Step 4: Add 10% waste 111.1 × 1.10 = 122.2 → order 123 tiles Step 5: Boxes (if 6 tiles per box) 123 / 6 = 20.5 → order 21 boxes Step 6: Grout (3mm joint, 10mm tile depth) kg/m² = 1.8 × 3 × 10 × (300 + 600) / (300 × 600) = 1.8 × 3 × 10 × 900 / 180,000 = 48,600 / 180,000 = 0.27 kg/m² Total grout = 0.27 × 20 = 5.4 kg → 2 × 5kg bags Step 7: Adhesive (floor = 5 kg/m²) 5 × 20 = 100 kg → 5 × 20kg bags Step 8: Cost (if $45 per box) 21 boxes × $45 = $945 for tiles

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Last updated: April 29, 2026 · Formula verified by EagleCalculator team · Eagle-eyed accuracy for every calculation.