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Floor Tile Calculator — Tiles, Adhesive & Grout for Any Room
Calculate how many floor tiles, adhesive and grout you need. Supports straight, diagonal and herringbone laying patterns.
Longest dimension of the room
Shortest dimension of the room
Room not a simple rectangle? An L-shaped room is just two rectangles: measure each one wall to wall and add it as a section. Use three sections for a T or U shape. The calculator adds every section together.
Adds 10% for Straight / Grid pattern
10% recommended for Straight / Grid pattern
Enter your tile price for a cost estimate
25kg bag default: 4.5 m² for standard tiles (6–10mm notch); ~3 m² for large-format 600mm+ (12mm notch + back-buttering)
Default: 5kg bags. Grout estimate assumes a 3mm joint and ~12mm depth (conservative) — check your grout datasheet for the exact tile thickness
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How We Calculate This
Our floor tile calculator divides your floor area by the area of each tile to determine the number of tiles needed. We then add wastage based on your laying pattern and calculate adhesive and grout quantities using UK product coverage rates.
For an L-shaped room, press Add section and enter each rectangle as its own section. Tile counts are rounded up per section and then added together, covering the extra cut tiles at the junction between sections, while adhesive and grout use the combined area because they are spread continuously. Use three sections for a T or U shape.
The formula
Tiles needed = (Floor area ÷ Tile area) × (1 + Wastage %)
For example, a 20 m² room with 300×300mm tiles in a straight pattern: 20 ÷ 0.09 = 222.2, rounded up to 223 tiles, + 10% wastage = 245.3, rounded up to 246 tiles.
Wastage by pattern
- Straight/grid: 10% — minimal cuts at edges
- Diagonal/diamond: 15% — more cuts at all walls
- Herringbone: 20% — many angled cuts required
Adhesive and grout
- Adhesive: a 25kg bag covers ~4.5 m² for standard tiles with a 6–10mm notched trowel, dropping to ~3 m² for large-format tiles (600mm+) where a 12mm notch plus back-buttering is needed for full bed coverage. The calculator sets this automatically and you can override it in Advanced Options.
- Grout: varies by tile size — smaller tiles need more grout per m² due to more joint lines. Our estimate assumes a 3mm joint at ~12mm depth (conservative); check your grout datasheet for the exact tile thickness.
Frequently Asked Questions
The number of floor tiles per m² depends on tile size: 150x150mm = ~44 tiles/m², 300x300mm = ~11 tiles/m², 450x450mm = ~5 tiles/m², 600x600mm = ~3 tiles/m², 300x600mm = ~6 tiles/m². Always add 10-20% wastage depending on your laying pattern and room shape. This floor tile quantity calculator rounds up for you automatically.
A 25kg bag of standard flexible floor tile adhesive covers approximately 4–5 m² using a 10mm notched trowel. Larger format tiles (600×600mm+) may need back-buttering, which increases adhesive use. For floor tiles, always use a flexible adhesive rated S1 or S2, especially over underfloor heating — see our Underfloor Heating Coverage Calculator to size your UFH.
For floor tiles (ceramic, porcelain or natural stone), always use flexible adhesive (classified as S1 or S2 deformable). Standard rigid adhesive is more prone to cracking underfoot. Flexible adhesive is essential over underfloor heating, wooden subfloors, and for large format tiles. Popular UK options include BAL Rapid-Flex, Weber Set Flex, and Mapei Keraquick.
Split the floor into rectangles and enter each one as its own section using the Add section button; the calculator adds the sections together for you. The tile count is rounded up for every section separately before being added, which allows for the extra cut tiles along the junction between sections and never under-orders. Adhesive and grout are worked out from the combined floor area, because both are mixed and spread continuously across the whole floor. Use three sections for a T or U shaped room, and consider a higher wastage percentage if the room also has alcoves or a bay.
For diagonal (diamond) laying patterns, allow 15% wastage. Straight/grid patterns need 10%, while herringbone patterns need 20%. Complex room shapes with alcoves or bay windows may need even more. You can adjust the wastage percentage in this calculator to match your room. Always keep spare tiles for future repairs — the same batch may not be available later.
Floor tiles require a flat, level substrate. If your floor has dips or bumps greater than 3mm over 2 metres, level it first. Use our Self-Levelling Compound Calculator for thin levelling (2–5mm), or our Screed Calculator for full screeding. After tiling, finish the room with skirting boards — our Skirting Board Calculator works out quantities.
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Last updated: February 2026
Verified against UK standards · estimates only, confirm with your supplier.