FlooringFree toolLast updated: March 27, 2026·TCNA standards
A 10×8 ft room (80 sq ft) with 12×12 inch tiles in a straight grid needs 88 tiles (10% waste per TCNA). That’s 9 boxes of 10. Switch to herringbone and you’ll need 96 tiles (20% waste) — 8 more tiles. Enter your dimensions below for an exact count with pattern-specific waste, box quantity, and complete materials list.
The formula is straightforward: divide your room area by the area of one tile, then add a waste percentage based on your layout pattern. According to the TCNA (Tile Council of North America) Handbook, a straight grid layout produces approximately 10% waste from edge cuts, while a herringbone pattern creates 20% waste due to the angled cuts at every wall. For a 10×8 ft bathroom (80 sq ft) with 12×12 inch tiles, you need 80 base tiles plus 8 for waste = 88 tiles total, or 9 boxes of 10.
Table of Contents
The most common mistake DIY tilers make is underestimating waste. The NTCA (National Tile Contractors Association) recommends always keeping at least one sealed box of spare tiles from the same dye lot for future repairs. Tiles from different manufacturing batches can have subtle color differences that become obvious when placed next to your original installation.
How does layout pattern affect tile quantity and cost?
Pattern choice is the single biggest variable in tile estimation after room size. Per TCNA guidelines, waste percentages by pattern are: straight grid 10%, brick/offset 12%, diagonal 45-degree 15%, herringbone 20%, and chevron 22%. On a 120 sq ft kitchen floor with $4/sq ft tile, the difference between straight ($528) and herringbone ($576) is $48 in extra tile alone — plus herringbone typically costs $3–5 more per square foot in labor due to the complexity of cuts.
How much grout and thinset do I need?
Grout quantity depends on tile size, grout joint width, and tile thickness. Per TCNA guidelines, use unsanded grout for joints 1/8 inch or narrower and sanded grout for wider joints. A 25-lb bag of sanded grout covers approximately 200 sq ft of 12×12 inch tile with 1/8-inch joints. Thinset mortar (the adhesive) coverage depends on trowel size: a 50-lb bag covers 75–100 sq ft with a standard 1/4×1/4 inch notched trowel, or 40–50 sq ft with a larger 1/2×1/2 inch trowel needed for large-format tiles (over 15 inches).
Frequently asked questions
How many tiles do I need for a 10×10 room?
A 10×10 ft room is 100 sq ft. With 12×12 inch tiles (1 sq ft each) and 10% waste: 100 × 1.10 = 110 tiles. With 12×24 inch tiles (2 sq ft each): 50 × 1.10 = 55 tiles. Always round up to full boxes.
How much extra tile should I buy for waste?
Per TCNA standards: 10% for straight grid, 12% for brick/offset, 15% for diagonal, 20% for herringbone, 22% for chevron. Add an extra 5% if your room has many obstacles (toilet, vanity, floor vents). Always buy at least 1 extra sealed box for future repairs from the same dye lot.
What size grout line should I use?
Standard grout width is 1/8 inch (3mm) for most floor tiles. Use 1/16 inch for rectified (precision-cut) tiles for a minimal grout look. Use 1/4 inch for natural stone or handmade tiles with irregular edges. Per TCNA: unsanded grout for joints ≤1/8 inch, sanded grout for wider joints.
Is herringbone tile more expensive?
Yes — herringbone requires 20% more tiles than straight layout (vs 10%), and labor costs $3–5 more per sq ft due to the complexity of angled cuts. For a 100 sq ft floor, expect to spend $30–50 more on tiles and $300–500 more on professional installation compared to straight grid.
How many boxes of tile do I need?
Divide your total tiles needed (including waste) by the number of tiles per box, then round up. If you need 88 tiles and boxes contain 10, you need 9 boxes. Always round up — stores sell full boxes only, and having extras from the same dye lot is essential for future repairs.
What is the difference between sanded and unsanded grout?
Unsanded grout is smooth and used for narrow joints (1/8 inch or less) — common with rectified tiles and wall tiles. Sanded grout contains fine sand for strength and is used for wider joints (over 1/8 inch) — standard for most floor tiles. Using the wrong type causes cracking or poor adhesion.
Waste factors based on TCNA (Tile Council of North America) Handbook. Grout and thinset coverage per manufacturer specs (Custom Building Products, Mapei). Professional guidelines per NTCA (National Tile Contractors Association). Costs reflect 2026 US retail averages.
HomeChisel