Tile Calculator

How to Calculate How Many Tiles You Need

Getting the right number of tiles for your project saves money and avoids delays. Our tile calculator takes the guesswork out of your renovation. If you are considering alternatives to tiles, try our flooring calculator for laminate, vinyl, or hardwood options.

The Tile Calculation Formula

Tiles needed = (Total Area ÷ Single Tile Area) × (1 + Waste Factor)

The effective tile area includes the grout joint width on two sides of each tile.

Step-by-Step Guide

1. Measure the area — Record length and width of the surface to be tiled.
2. Choose your tile size — Common sizes: 30×30cm, 45×45cm, 60×60cm.
3. Select grout width — Standard is 3mm for rectified tiles, 5mm for rustic.
4. Add waste factor — 10% minimum, more for complex patterns.

Materials You'll Need Beyond Tiles

Choosing the Right Tile Layout

• Straight lay — Simplest, least waste (5-10% extra)
• Diagonal/Diamond — More visual interest, higher waste (15-20% extra)
• Herringbone — Premium look, complex cuts (15-20% extra)
• Brick/Offset — Good for rectangular tiles (10-15% extra)

Tile Material Comparison

Material choice drives both price and where the tile can be used. Porcelain is the most versatile; natural stone is the most demanding.

Outdoor floors and shower floors must use porcelain rated R10 or higher (slip resistance) and frost-proof if exposed to freezing.

Grout, Adhesive, and Backer Board

Materials beyond the tile itself add 20-30% to a typical tiling budget. Get the right type the first time:

Use C2 flexible adhesive for any floor with underfloor heating — rigid C1 cracks as the substrate expands.

Layout Patterns and Waste Factors

Pattern complexity changes how many tiles end up cut and discarded. Order accordingly:

Large-format tiles (60×60 cm and up) need a perfectly flat substrate (within 3 mm over 2 m) — otherwise "lippage" at corners is unavoidable.

Common Mistakes to Avoid

• Not buying enough — Always order 10% extra minimum. Tile batches can vary in shade.
• Wrong adhesive — Use flexible adhesive for floor heating, waterproof for wet areas.
• Skipping waterproofing — Essential for bathrooms and kitchens near water.
• Ignoring tile direction — Check if tiles have a directional pattern before laying.
• Forgetting the subfloor — If you are tiling on a new concrete base, use our concrete calculator to get the slab quantity right before you start.
• Mixing batches mid-room — Even within the same product, batches vary slightly. Open all boxes first and mix tiles between them as you lay.

When to Hire a Professional Tiler

Professional tiling is recommended for bathrooms (waterproofing is critical), large-format tiles (60cm+), complex patterns, and heated floors. A skilled tiler ensures waterproof joints and level surfaces. Once the tiling is done, estimate the wall paint above the tiled area with our paint calculator.

Tile Waste: How Many Extra Tiles to Buy

Tile waste is the extra material lost to cuts, breakage, and pattern fitting. Underestimating waste leads to frustrating mid-project shortages, while overestimating wastes money on unused tiles. Plan for 10% waste on standard straight-lay patterns, 15% for brick/offset patterns, and 15-20% for diagonal or herringbone layouts. Small or irregularly shaped rooms may need up to 20% extra.

Why Different Patterns Produce Different Waste

The key factor is how many tiles need to be cut along the room's edges:

• Straight lay — Tiles align with the walls. Only tiles along two edges (one length and one width) need cutting. Offcuts from one side can sometimes be used on the opposite side.
• Brick bond — Each row is offset by half a tile, so every other row starts with a half-cut tile. However, cuts are all straight, so a manual tile cutter is sufficient.
• Diagonal — Every tile along every wall edge needs an angled cut. The triangular offcuts are too small to reuse, creating significantly more waste.
• Herringbone — Tiles are set at alternating 45° angles. Every perimeter tile needs a precise angled cut, and the interlocking pattern means offcuts rarely fit elsewhere.

Room Shape and Its Impact on Waste

Room complexity affects waste as much as pattern choice:

Add these to the pattern waste factor. For example, a diagonal pattern in an L-shaped room needs 15-20% (pattern) + 2-3% (shape) = 17-23% waste factor.

Worked Example: How Many Tiles for a Herringbone Floor

1. Calculate the net area (length × width)
2. Choose your waste factor from the tables above
3. Multiply: Total tiles = Net area × (1 + Waste factor)
4. Round up to the nearest full box
5. Add 2-3 spare tiles for future repairs

For a 15 m² floor in a herringbone pattern:

• 15 × 1.20 = 18 m² of tiles needed
• At 30×60cm tiles (0.18 m² each): 18 ÷ 0.18 = 100 tiles
• With 4 tiles per box: 25 boxes

The Cost of Getting Waste Wrong

Waste is not just about tiles — every wasted tile also wastes adhesive, grout, and time. Here's the financial impact:

Choosing a straight lay over a diagonal pattern in a 30 m² room can save €75+ in tile cost alone, not counting the simpler installation. Consider whether the aesthetic difference justifies the extra expense.

Reducing Waste: Practical Strategies

Not all waste is unavoidable. Here are proven ways to minimise it:

1. Plan your layout before buying — Draw the room to scale and map out tile placement. Many tile retailers offer free layout planning software.
2. Start from the centre — This equalises the cuts on both sides of the room, making offcuts more consistent and reusable.
3. Choose tiles that fit your dimensions — If your room is 3m wide and you use 60cm tiles, you get exactly 5 tiles across with zero cuts.
4. Save large offcuts — Keep any cut piece larger than half a tile. These can fill gaps on the opposite wall or in closets.
5. Use a quality tile cutter — A good manual cutter or wet saw produces clean cuts, reducing breakage waste. Cheap cutters shatter tiles.
6. Order from the same batch — All tiles should come from one production batch (same lot number) to ensure colour consistency.

What to Do with Leftover Tiles

If you do end up with extra tiles:

• Store 4-6 tiles flat and dry for future repairs
• Use offcuts for small projects (coasters, plant pot stands, mosaic art)
• Return unopened boxes — most retailers accept returns within 30-90 days with receipt
• Sell or give away remaining tiles through local marketplace apps

Kitchen Tiling: Backsplash and Floor

Kitchen tiling typically covers two areas: the backsplash (the wall between countertops and upper cabinets) and the floor. Each has different dimensions, tile size preferences, and material needs.

Kitchen Backsplash Calculation

A backsplash is usually 55-65cm high (the gap between counter and upper cabinets) and runs the length of your countertop. The calculation is straightforward:

Tiles needed = (Backsplash Length × Height) ÷ Single Tile Area × 1.10

For a standard 3m backsplash that's 60cm high:

• Area = 3 × 0.6 = 1.8 m²
• Using 10×10cm tiles: 1.8 ÷ 0.01 × 1.10 = 198 tiles (round up to 200)
• Using subway tiles (10×20cm): 1.8 ÷ 0.02 × 1.10 = 99 tiles (round up to 100)

Popular Kitchen Tile Sizes and Layouts

Kitchen Floor Tile Calculation

Kitchen floors require the same calculation as any floor: Length × Width, plus waste. However, kitchens often have irregular shapes (L-shaped, island cutouts), so measure in sections:

1. Measure the main rectangular area
2. Add any alcoves or extensions
3. Subtract the island base (if permanently fixed)
4. Add 10-15% waste

Backsplash Materials Checklist

For a 1.8 m² backsplash, you'll typically need:

Kitchen-Specific Tile Considerations

Kitchens have unique demands on tile and grout:

Heat resistance — The area behind your hob or range is exposed to heat and grease splatter. Porcelain and ceramic tiles handle this easily. The real concern is the grout — use epoxy grout behind the stovetop as it resists grease staining.

Stain resistance — Kitchens generate oil, wine, coffee, and food stains. Choose tiles with low porosity (porcelain is best) and stain-resistant grout. Glossy-finish tiles wipe clean more easily than matte.

Cleaning ease — Larger tiles with narrow grout lines are the easiest to clean. Every grout line is a potential dirt trap. If using small-format tiles, seal the grout after installation.

DIY Kitchen Backsplash: Step by Step

A kitchen backsplash is one of the best beginner tiling projects because the area is small, the tiles are lightweight, and imperfections are less noticeable at counter height.

1. Prepare the surface — Clean the wall, fill any holes, and apply a primer if the wall is dusty or porous.
2. Plan your layout — Dry-fit a row of tiles along the countertop to determine your starting point. Centre the layout so edge cuts are equal on both sides.
3. Apply adhesive — Spread wall tile adhesive with a notched trowel. Work in sections of 0.5 m² at a time so the adhesive doesn't dry out.
4. Place tiles — Press each tile firmly into the adhesive with a slight twist. Use spacers between tiles for even grout lines.
5. Cut tiles — A manual tile cutter handles straight cuts. Use tile nippers for notches around outlets and pipes.
6. Grout — After the adhesive has set (24 hours), apply grout with a rubber float, pressing it into the joints diagonally.
7. Seal and finish — Apply silicone sealant where the backsplash meets the countertop and at any inside corners.

Cost Comparison: Kitchen Tiling Options

Bathroom & Wet-Area Tiling

Bathroom tiling is one of the most impactful renovations you can make, but it requires careful planning. Bathrooms have unique requirements — waterproofing, slip resistance, and moisture-resistant grout — that set them apart from tiling other rooms.

Bathroom Tile Calculation: Floor vs Walls

Floor tiles: Length × Width of the floor area, divided by the area of a single tile, plus waste.

Wall tiles: Calculate the area of each wall separately (height × length), subtract any windows, then divide by single tile area plus waste.

For a bathroom measuring 2.5m × 3m with 2.5m ceiling height:

Choosing Bathroom Tiles by Area

Different bathroom zones have different requirements:

Waterproofing: The Critical Step

Waterproofing is non-negotiable in bathrooms. Water that gets behind tiles causes mould, structural rot, and costly damage. Here's what you need:

• Liquid membrane — Apply 2 coats with a roller over the entire wet area. Coverage is approximately 1-1.5 L per m² for two coats.
• Reinforcing tape — Use in corners and at wall-floor junctions where movement and cracking are most likely.
• Drying time — Allow 24 hours for the membrane to fully cure before tiling over it.
• Coverage area — At minimum, waterproof the shower zone. Best practice is to waterproof the entire bathroom floor and all walls to at least 1.8m height.

Materials List for Bathroom Tiling

Floor Tiles vs Wall Tiles: Key Differences

Not all tiles are interchangeable between floors and walls:

• Floor tiles must have a slip rating (R9 minimum, R10-R11 preferred for wet areas). They're thicker (8-10mm) and made from denser porcelain.
• Wall tiles can be thinner ceramic (6-8mm) and don't need a slip rating. They're lighter, which prevents them pulling away from the wall under their own weight.
• Floor tiles can go on walls (if the wall structure supports the weight), but wall tiles should never go on floors.

Grout for Bathrooms

Standard grout absorbs moisture and can grow mould. For bathrooms, always use:

• Epoxy grout — Completely waterproof and mould-resistant. More expensive (€8-15/kg) but lasts the life of the tiles.
• Anti-mould cementitious grout — A budget alternative (€3-5/kg) with fungicide additives. Effective but may need resealing every few years.
• Silicone sealant — Use in corners, edges, and where tiles meet the bathtub or shower tray. Grout cracks in these movement zones; silicone flexes.

For a dedicated shower enclosure, see our shower tiling calculator to size tiles, waterproofing, and trim precisely.