Tile Calculator
Work out exactly how many tiles and boxes to buy for a floor or wall — with a waste allowance built in so you don't come up short.
How this calculator works
The calculator first finds your room area (Length × Width, in square feet), then finds the area of a single tile by converting its length and width from inches to square feet: (tile length in × tile width in) ÷ 144 (144 square inches in a square foot).
A waste allowance is added to the room area to cover cuts, breakage, and pattern layout (diagonal or offset patterns need more). The number of tiles is the waste-adjusted area divided by the area of one tile, rounded up. Boxes needed is that same area divided by how many square feet one box covers, rounded up to a full box.
Example calculation
Project: a 12 ft × 10 ft bathroom floor, using 12″ × 12″ tiles sold in boxes covering 15 ft² each, with 10% waste.
- Room area = 12 × 10 = 120 ft²
- With 10% waste = 120 × 1.10 = 132 ft²
- One tile = (12 × 12) ÷ 144 = 1 ft²
- Tiles needed = 132 ÷ 1 = 132 tiles
- Boxes needed = 132 ÷ 15 ≈ 9 boxes
Buying & material guidance
Straight-lay patterns typically need only 7–10% waste; diagonal layouts, herringbone, or rooms with lots of corners and cutouts (like bathrooms with fixtures) should use 15% or more. Large-format tiles (anything over 15″) also tend to need more waste allowance since offcuts are harder to reuse.
Always buy tile from the same dye lot when possible — color can shift slightly between production runs. It’s also worth keeping a full spare box after the job for future repairs, since matching tile years later is often impossible.
Frequently asked questions
How many tiles do I need for a 12x12 room?+
For a 12 ft × 10 ft room (120 ft²) using standard 12x12-inch tiles with a 10% waste allowance, you'd need about 132 tiles — roughly 9 boxes if each box covers 15 square feet.
How much extra tile should I buy for waste?+
A 10% waste allowance covers most straight-lay installations. Increase this to 15% or more for diagonal patterns, herringbone layouts, or rooms with many cuts around fixtures and corners.
Should I buy tile by the box or by the piece?+
Tile is almost always sold by the box, and most retailers require full-box purchases. This calculator rounds up to the nearest full box so you know exactly how many to order.