How many floor tiles do I need per m²?

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.

How much tile adhesive do I need for floor tiles?

A 25kg bag of standard flexible floor tile adhesive covers approximately 4-5 m² using a 10mm notched trowel. Larger format tiles (600x600mm+) 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 (/flooring/underfloor-heating-coverage-calculator) to size your UFH.

Should I use flexible or standard adhesive for floor tiles?

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.

What wastage should I allow for diagonal tiling?

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.

Do I need to level the floor before tiling?

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 (/flooring/self-levelling-compound-calculator) for thin levelling (2-5mm), or our Screed Calculator (/flooring/screed-calculator) for full screeding. After tiling, finish the room with skirting boards — our Skirting Board Calculator (/flooring/skirting-board-calculator) works out quantities.

TradeCalcs

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.

Room Length

Room Width

Tile Size

Laying Pattern

Include wastage allowance

Adds 10% for Straight / Grid pattern

Wastage Percentage

10% recommended for Straight / Grid pattern

Price Per Tile (optional)

Enter your tile price for a cost estimate

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.

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 = 223 tiles + 10% = 245 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: 25kg bag covers 4-5 m² (10mm notched trowel)
Grout: Varies by tile size — smaller tiles need more grout per m² due to more joint lines

Frequently Asked Questions

Related Calculators

Screed Calculator

Calculate screed volume and sand/cement quantities for floor screeding.

Self-Levelling Compound Calculator

Work out how many bags of self-levelling compound you need.

Laminate Flooring Calculator

Work out how many packs of laminate or engineered flooring you need.

Carpet Calculator

Calculate carpet area, underlay and gripper rod quantities.

Underfloor Heating Coverage Calculator

Calculate UFH mat or cable coverage for your floor area.

Last updated: February 2026

All calculations are estimates. Verify with your supplier.