How many tiles do I need?
A useful tile calculator needs to separate three quantities that are often confused: the net surface you intend to tile, the allowance you add for cuts and breakage, and the actual quantity you can purchase in whole boxes. Numbivo shows all three instead of hiding the rounding inside one number.
In Length × width mode, enter the dimensions of a rectangular floor or wall. In Known surface area mode, enter a measured takeoff directly. Doors, windows, niches or other untiled areas can be subtracted separately. The calculator then divides the net area by the face area of one tile and rounds up to a whole piece.
Where to get the tile, adhesive and grout input data
Tile dimensions, box contents and project area
Measure the finished surface or take the area from drawings, then subtract only areas that genuinely will not be tiled. Use the actual tile dimensions and pieces per box from the carton or product sheet rather than relying only on a nominal format such as 60 × 60 cm or 12 × 24 in.
Adhesive and grout product data
Use the adhesive technical data or manufacturer coverage calculator for the selected trowel, substrate and tile format. For grout, use the planned joint width, approximate filled joint depth and the product density or manufacturer consumption data. Package weights and prices should come from the exact product you intend to buy.
Best final check: compare the Numbivo order quantity with the box coverage and product-specific adhesive/grout coverage printed by the manufacturer. Site conditions and application method can change real consumption.
Tile waste for straight, diagonal and patterned layouts
Waste is not only breakage. It also covers edge cuts, awkward corners, pattern alignment and pieces that cannot be reused elsewhere. A simple rectangular room with a straight grid may need a modest allowance, while diagonal layouts or complex patterns can create substantially more cutting.
The layout selector therefore changes only the suggested waste percentage. It does not pretend to simulate every cut. You can overwrite the percentage at any time. If you have a detailed layout plan or a supplier recommendation, use that instead of the preset.
Boxes can add more spare tile than the waste percentage
If your estimate needs 37 tiles and the product contains four tiles per box, you must buy ten boxes, or 40 tiles. That packaging step creates additional coverage beyond the waste percentage you entered. The result panel shows purchased coverage and coverage above the net tiled area so you can see that difference.
Keeping a few matching spare tiles can be useful for future repairs, especially because shade or calibre can vary between production batches.
Tile adhesive calculator: use the product coverage rate
Tile adhesive consumption depends on the adhesive, trowel notch, substrate flatness, tile format, installation method and whether back-buttering is required. Large-format tiles can use more material than a simple area rule suggests. That is why the adhesive rate in this calculator is deliberately editable.
Enter the mass of adhesive used per square metre, or the equivalent US rate shown by the calculator, then enter the package weight. Numbivo calculates the theoretical adhesive mass from the net tiled area and rounds the package count up. If the manufacturer specifies coverage per bag for your trowel and tile size, convert that information into a rate or adjust the result to the manufacturer's guidance.
Grout calculator from tile size and joint dimensions
Grout demand is driven by more than floor area. Smaller tiles create more joint length per square metre, and wider or deeper joints create a larger joint volume. The calculator therefore uses the tile width and length together with the grout-joint width and depth.
The geometric joint volume is converted to mass with an editable grout density and then increased by the grout allowance. This is useful for comparing two tile formats: covering the same 12 m² with small tiles usually creates much more joint length than covering it with 60 × 60 cm tiles.
The formula is an estimating model for a regular grid. Edge details, rounded tile profiles, irregular handmade tiles, mosaics and installation losses can change real consumption. Product calculators or technical data remain the best final check for a specific grout.
Floor tiles, wall tiles and backsplashes
The same quantity logic works for floors and walls. For a backsplash or shower wall, use surface width × height and subtract any area that will not be tiled. For several separate walls, add their areas and use Known surface area. If different walls use different tile formats, calculate them separately rather than averaging the tile sizes.
Optional material cost
Enter the local price per tile box, adhesive package and grout package to create a basic material budget. The total deliberately excludes labour, waterproofing membranes, decoupling systems, trims, spacers, levelling clips, primer, self-levelling compound, delivery and tools because those costs vary independently of the tile count.
For tiling students and apprentices: read the takeoff in stages
A useful training exercise is to keep surface area, tile count, waste and packaging separate. For a 4 × 3 m floor with 60 × 60 cm tiles, 10% waste and four tiles per box:
- Net tiled area = 4 × 3 = 12 m².
- One tile face area = 0.60 × 0.60 = 0.36 m².
- Area including 10% waste = 12 × 1.10 = 13.20 m².
- Tiles to order = round up(13.20 ÷ 0.36) = 37 tiles.
- Boxes = round up(37 ÷ 4) = 10 boxes, which means 40 purchased tiles.
With the example 4 kg/m² adhesive rate, the same 12 m² surface uses about 48 kg of adhesive. With 3 mm wide × 8 mm deep joints and the example grout density, the grout estimate is about 1.80 kg including 10% grout allowance.
Check question: why does the calculator show 40 purchased tiles when the waste-adjusted quantity is 37? Because tiles are sold in whole boxes. Packaging creates an additional rounding allowance beyond the selected waste percentage.
Tile estimating scenarios
Load an example directly into the calculator or reveal its result. The live calculator and the scenario answer use the same assumptions.
12 m² floor with 60 × 60 cm tiles
4 × 3 m floor, straight layout, 10% tile waste, four tiles per box, 4 kg/m² adhesive and 3 mm × 8 mm grout joints.
Bathroom walls with an opening
18 m² measured wall area minus 2 m² untiled area, 30 × 60 cm tiles, diagonal-style 15% allowance and six tiles per box.
US floor with 12 × 24 in tiles
120 ft² floor, 12 × 24 in tiles, 10% allowance, six tiles per box and editable US adhesive and grout inputs.
Before ordering tile, adhesive and grout
Confirm the exact tile dimensions, pieces per box and box coverage printed by the manufacturer. Nominal tile sizes can differ slightly from actual dimensions, and mixed-format patterns need a dedicated layout rather than a single-tile area calculation. For a visually continuous project, ordering the full quantity from one batch is often preferable to relying on a later top-up.
Also verify substrate preparation, movement joints, waterproofing requirements, adhesive class, grout-joint limits and installation instructions for the chosen tile system. The calculator is a material estimator, not a substitute for the product specification or a project-specific installation design.
Learn the estimating method
Go deeper into the method or check reference values without losing the context of this calculation.