Bathroom Tile Calculator
Estimate tile and box quantities for a bathroom floor or wall, accounting for the fixtures and cuts bathrooms typically involve.
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.
This tool uses the same calculation engine as our full Tile Calculator, with guidance tailored to this project type.
Frequently asked questions
How much waste allowance for a bathroom floor?+
Use 15% instead of the standard 10% for bathrooms — the toilet flange, vanity, and tight corners create more cuts and offcuts than a typical open room.
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.