Tile Grout Coverage Calculator — m² tiles, thinset, cost
How to use this calculator
Pick the room shape, enter dimensions in m, cm or mm, then choose tile size and grout joint — the count reflects nominal tile + joint (a 300×300 mm tile on a 3 mm line covers 303×303 mm). Pattern auto-sets waste: 0% straight grid, +10% running bond, +15% diagonal/herringbone. Bag and sheet outputs drive a real materials list you can hand to the merchant without re-doing math on the desk. Working in square feet instead? Use the imperial grout calculator for ft² areas and 25 lb bags.
Cost — price per tile or per box, thinset per bag, grout per bag, backer board per sheet; the grand total sums only the optional sections you enable. Choose your currency in settings below.
Thinset — a 25 kg bag covers ~5 m² with a 6×6 mm notch, ~4 m² with 6×8 mm, and ~3 m² with 10×10 mm (EN 12004, class C1/C2).
Grout — volume is computed from joint width × tile thickness × joint length, then divided by ~5,900 cm³ per 10 kg bag (EN 13888, CG1/CG2).
Backer board — cement board in 900×1500 mm sheets (1.35 m²), 10% added for cuts.
(tile perimeter × joint × depth × density) ÷ 2 ÷ tile area. Joints are shared between two tiles, so ÷2. Depth = tile thickness; density = 1.6 kg/L for cementitious CG1/CG2; a 15% overage buffer is added for absorption and touch-ups (editable below).Saved Calculations
| Time | Shape | Area m² | Tile | Tiles | Thinset | Grout | Backer | Total |
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Tile grout calculator for m² floors and walls
Net tiles = floor area ÷ (tile width + joint)(tile height + joint), rounded up; the joint is added so a 300×300 mm tile on a 3 mm grout line actually covers 303×303 mm. Pattern waste is then applied: a straight grid loses almost nothing, a running-bond offset wastes ~10%, and 45° diagonal or herringbone wastes ~15% from edge cuts. Order full boxes and keep one spare box for repairs.
Thinset mortar coverage (EN 12004)
Coverage tracks trowel notch: a 6×6 mm notch spreads a 25 kg bag over ~5 m², a 6×8 mm notch over ~4 m², and a 10×10 mm notch (large-format / uneven substrate) over ~3 m², consistent with EN 12004 C1/C2 adhesive classes. Back-buttering large tiles uses more. On gypsum substrates, size the board with the drywall sheet & tape calculator.
Grout coverage formula (EN 13888)
Use this as a metric grout coverage calculator when the search question is "how much grout per m2". Wet joint volume per tile = (tile perimeter × joint width × tile thickness) ÷ 2 (joints are shared between two tiles); summed over the tile count, multiplied by grout density (1.6 kg/L for cementitious CG1/CG2 per EN 13888) and a 15% overage buffer for absorption and touch-ups. A 10 kg bag covers roughly 30–50 m² for a 300×300 mm tile on a 3 mm joint — the tool reports kg/m² and total kg so you can match a specific product chart (Mapei Ultracolor, Ardex FL). Smaller tiles, wider joints, and thicker porcelain raise grout use; epoxy grout (~1.8 kg/L) consumes more.
Tile layout, cut list and layout-driven waste
This is also a tile layout planner: the plan view draws every tile in place, full tiles in blue and perimeter cuts in orange (sliver cuts under 50 mm in red), with a cut list below giving the exact millimetre dimension of each trimmed piece by edge. Layout-driven waste is computed from the actual cut count, not a flat percentage — a 600×600 mm tile in a 1.5×1.5 m room genuinely wastes ~29% from perimeter cuts, while a 300×300 mm tile in a room sized to a full grid wastes almost nothing. Use Layout Start (corner or center) and the Manual Offset slider to shift the grid and balance the edges — center start gives symmetric perimeter cuts on opposite walls, preferred for visible rooms. For multiple spaces (bath floor + shower walls + niche), add each as a room and the totals, boxes, and cost sum across all of them.
On install day
Three estimator misses we see all the time. Round to full boxes — a 10 m² floor at 300×300 mm is roughly 122 tiles with 10% waste, but a typical box holds 6–11 tiles, so you almost always pay for one extra box; keep that spare for repairs. Backer board, not plasterboard — wet rooms need cement board (900×1500 mm sheets, 1.35 m² each) under tile per EN 12004 substrate guidance; the calculator adds 10% for cuts and seams. Adhesive and grout pricing in 2025 EU — 25 kg modified thinset (C2TE) is €10–18/bag, 5 kg cementitious grout (CG2) €6–14/bag, basic ceramic tile €8–25/m² and porcelain €20–60/m²; large-format tiles need 10×10 mm notches and back-buttering, which raises bag count 20–30%. Comparing finishes? See the flooring pack calculator or the carpet calculator, and the paint calculator for the walls. Tiling onto masonry? Cross-check with the block wall calculator.
