Tile Calculator
Compute tiles needed for any floor or wall area. Counts each tile with its joint, estimates grout from the joint volume, and adds a waste allowance by pattern.
Tile Calculator
How to use the Tile Calculator
Measure the area to be tiled
For floors: measure length and width tip-to-tip along the room's longest dimensions. For walls (bathroom backsplash, shower surrounds): measure each wall separately and add the areas. For L-shaped rooms, split into rectangles and run the calculator for each. Always measure twice — a 1-inch error on a 12-ft wall is one tile's worth of difference and can mean an extra box at checkout.
Enter the tile's actual size, joint and thickness
Use the face dimensions on the manufacturer's specification, which can differ from the nominal size on the box, then the joint width you plan and the tile thickness. Each tile occupies its face plus one joint in each direction, which this page now includes; the thickness sets the joint depth for the grout estimate.
Set a waste allowance for the pattern
The pattern menu suggests a starting allowance — 10% for a straight grid, 15% for diagonal and 20% for herringbone or mosaic — because patterns with more edge cuts leave more offcuts that cannot be reused. These are common allowances, not a standard; set your own.
Check the dye lot at purchase
Every tile box has a dye-lot or batch number on the label. Tiles from different lots can vary visibly in color — natural stone (marble, travertine, slate) is the worst offender, but porcelain and ceramic also drift across runs. Always order all tiles for one project in one purchase, and confirm at checkout that all boxes share the same lot number. The 10% waste buffer is your insurance against finding out you need more from a now-unavailable lot.
Tile and grout quantities — the joint, the allowance and the formula
A tile laid with a joint occupies its own face plus one joint each way, so the count is the floor area divided by (length + joint) × (width + joint), plus an allowance. On the sample floor — 12 × 10 ft in 24-inch tiles with ⅛-inch joints — that is 29.7 tiles before the allowance and 33 with 10%, six boxes of six. This page used to divide by the tile face alone, which overcounts slightly; the gap matters more as tiles get smaller.
How grout is estimated
Grout use follows the volume of the joints: kilograms per square metre = (L + W) ÷ (L × W) × joint width × joint depth × a density factor, with sizes in millimetres. With a factor of 1.6 this reproduces the coverage table on MAPEI's Ultracolor Plus FA data sheet within a few per cent — for example, 300 × 300 × 10 mm tiles with 3 mm joints, where MAPEI gives about 14.5 m² per 4.54 kg bag. This page now uses the tile's own thickness as the joint depth; it used to assume 8 mm. Your grout's data sheet is the final word.
Small tiles mean more joint per square metre — and more grout.
Buying
Buy all the tile at once and check that every box has the same batch or shade code, because tiles from different production runs can differ in shade. Keep a few spare for later repairs.
The joint in every tile's footprint, and the joint volume behind the grout kilograms
Each tile occupies (length + joint) × (width + joint), not just its face.
Nominal and actual sizes can differ; use the face dimensions on the manufacturer's specification.
The sample 12 × 10 ft floor in 24-inch tiles with ⅛-inch joints takes 29.7 tiles, 33 with 10%.
Grout: kg/m² = (L + W) ÷ (L × W) × joint width × joint depth × density (mm, kg/dm³).
With a density of 1.6 the formula matches MAPEI's Ultracolor Plus FA coverage table within a few per cent.
MAPEI gives about 14.5 m² per 4.54 kg for 300 × 300 × 10 mm tiles with 3 mm joints.
For 610 × 610 × 10 mm tiles with the same joint it gives about 28.9 m² — twice the area, because larger tiles have less joint.
Joint depth is the tile thickness; this page used to assume 8 mm for every tile.
Grout scales with joint length per area, which rises as tiles get smaller.
Check every box for the same batch or shade code before you start.
Frequently Asked Questions
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Because offcuts from edge and corner cuts often cannot be reused, some tiles break, and buying more later risks a different batch. The 10% for a straight grid, 15% for diagonal and 20% for herringbone or mosaic suggested here are common allowances, not a published standard; more cuts mean more waste.
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Tiles are made in production runs, and shade can vary slightly from run to run; manufacturers mark each box with a batch or shade code. Buy all the tile for a job with the same code, and check before laying.
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Porcelain is a denser, lower-absorption kind of ceramic tile, which suits wet and outdoor areas. For quantities it makes no difference; for adhesive, grout and cutting, follow the tile manufacturer's specification.
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Follow the tile and grout manufacturers' recommendations for your tile, which depend on its size and how straight its edges are. MAPEI's Ultracolor Plus FA, for example, is made for joints from 1.5 mm to 19 mm. Enter the joint you choose; wider joints take more grout.
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It computes the volume of the joints, and with a density factor of 1.6 it matches MAPEI's own coverage table for Ultracolor Plus FA within a few per cent. Real use is a little higher because of waste in mixing and cleaning, and other grouts have different factors, so check your product's data sheet and buy a little extra.
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Use the type the grout manufacturer specifies for your joint width and tile; products state the range of joint widths they are made for.
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Break the room into rectangles. For an L-shape, two rectangles; for a T, three rectangles; for complex layouts, draw it on graph paper and decompose. Run the calculator once per rectangle, sum the tile counts. For each individual rectangle, the waste buffer applies — meaning a 2-rectangle L-shaped room will end up with slightly more total waste than a single-rectangle equivalent area. That's correct: more perimeter = more cuts = more waste. For very small rectangles (under 2 m² / 20 ft²), bump waste to 15% even on straight patterns, because single-tile rounding-up has bigger impact on small areas.
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Same calculator works for walls — measure wall length × wall height in place of floor length × width. For shower walls, subtract the niche / shelf areas separately (run a quick second calc for those areas). For kitchen backsplashes, measure the linear length of countertop × the height up to upper cabinets (typically 18 inches / 46 cm). Backsplashes commonly use smaller mosaic tiles (1×1 to 4×12 inch), which require 15–20% waste due to higher cut frequency. The pattern dropdown handles this; pick "complex" for any mosaic.
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No. All calculations run entirely in your browser via JavaScript. There's no server roundtrip — open DevTools → Network and confirm zero outbound requests as you change inputs. Room and tile dimensions stay on your device. Safe for confidential commercial estimates, project planning, or any room data that shouldn't leave your machine. Close the tab and nothing remains.
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Varies by tile size + box configuration. Typical counts: 6×6 inch (15×15 cm) tiles: ~25 per box. 12×12 inch (30×30 cm): ~10–15 per box. 24×24 inch (60×60 cm): ~4–6 per box. Plank tiles (8×40 inch / 20×100 cm): ~5–8 per box. The exact count varies by brand — always check the product page or box label. The "Tiles per box" field defaults to 6 (good guess for large-format tile); change it to match your specific product to get an accurate box count.
Method & sources
How it computes
Tiles = area / ((L + joint) x (W + joint)) x (1 + allowance), rounded up; boxes = tiles / per box. Grout kg/m2 = (L + W)/(L x W) x joint width x joint depth (tile thickness) x 1.6, mm and kg/dm3, matching MAPEI's Ultracolor Plus FA coverage table within a few per cent. RecaBuild.tiles / groutKgPerM2, tested.
What this tool implements
- Bug fixed: the tile count divided the floor by the tile face and ignored the joint, slightly over-counting (more for small tiles). Grout used a fixed 8 mm joint depth and a 1.5 kg/L factor; a tile-thickness input now sets the depth and the factor is 1.6, which reproduces MAPEI's published coverage (e.g. 14.5 m2 per 4.54 kg for 300 x 300 x 10 mm tiles at a 3 mm joint) within 5%, pinned by tests on three of its rows.
- Waste allowances by pattern (10 / 15 / 20%) are kept as suggested starting points, no longer called standard. Removed as unsourced or wrong: grout rules of thumb in kg/m2, nominal-size under-ordering percentages, ASEAN supplier and price claims, PEI and absorption figures, and trivia including tiles in the Step Pyramid of Djoser dated 'around 4000 BC' (the pyramid is about 2650 BC) and Burj Khalifa tile areas.
Sources
- MAPEI. Ultracolor Plus FA technical data sheet: coverage per 4.54 kg (10 lb) by tile size and joint width (1.5-19 mm). https://pdf.lowes.com/productdocuments/c7d8134d-911b-4467-a428-7e…
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