How Many Tiles Do I Need for a Bathroom Floor?

Updated October 2, 2026

A small 5 × 8 ft bathroom floor (40 sq ft) takes about 44 sq ft of tile once you add 10% for cuts. That's about 22 tiles at 12 × 24 inches, or 44 tiles at 12 × 12. Here's how to measure and plan your own floor. The tile calculator does the math, including grout.

Step 1: Measure the floor you'll actually tile

• Measure wall to wall in feet and multiply length × width.
• Subtract anything that sits on a permanent base and won't be tiled under, like a built-in tub or a shower pan. A standard 5 ft alcove tub takes about 12.5 sq ft.
• Include the space under a toilet and under freestanding vanities, which are usually tiled under.
• For an L-shaped room, split it into rectangles and add them.

Step 2: Pick the waste allowance

Bathrooms have lots of cuts around the toilet, door casing and tub, so they waste more than an open kitchen floor.

• 10%: straight layout, tiles 12 inches or smaller
• 15%: diagonal, offset patterns, or large tiles (12 × 24 and up) in a small room
• 20%: herringbone or complex patterns

Step 3: Convert to tiles and boxes

tiles = area × 144 ÷ ((tile width + joint) × (tile length + joint))
tiles to buy = tiles × (1 + waste %)
boxes = tiles to buy ÷ tiles per box, rounded up

Mosaics come on mesh sheets that are usually about 1 sq ft each, so for mosaics the number of sheets is roughly your square footage plus waste.

Worked example: 5 × 8 ft bathroom

For large tiles in a small room, use 15% instead: you'll often cut most of the tiles along the walls, and a single broken 24 × 24 tile is a big share of the order.

Grout and thinset

• Grout: large tiles with narrow joints need very little. 40 sq ft of 12 × 24 tile with 1/8 inch joints needs only a few pounds of grout. Mosaics use far more, because there are so many joints. The calculator estimates it for your tile size.
• Thinset mortar: a 50 lb bag typically covers roughly 40–95 sq ft depending on the trowel notch. Larger tiles need a bigger notch and therefore more thinset; check the coverage chart on the bag.
• Underlayment: over a wood subfloor, most tile goes over cement board or an uncoupling membrane, sold by the sheet or roll. Order it to the floor area plus a little extra.

Before you buy

• Check that every box shows the same lot (shade) number.
• Keep two or three spare tiles after the job for future repairs.
• Use tiles rated for floors, and look for a slip-resistance rating suitable for wet areas.