Flooring Calculator for Tile
A floor tile calculator for any room shape: enter the floor as one or more rectangles, pick a tile size and layout, and get tiles, boxes, grout, thinset and cost, with a drawing of the layout.
A 10×12 ft floor (120 ft²) needs 65 tiles of 12×24 in with 1/8 in joints and 10% extra.
ft² · ft² with % extra · ft² per tile
Tiles for common room sizes
| Room | Size | Area | 12×12 in | 12×24 in | 24×24 in |
|---|---|---|---|---|---|
| Half bath | 5 × 6 ft | 30 ft² | 33 | 17 | 9 |
| Full bathroom | 5 × 8 ft | 40 ft² | 44 | 22 | 11 |
| Large bathroom | 8 × 10 ft | 80 ft² | 87 | 44 | 22 |
| Laundry room | 6 × 8 ft | 48 ft² | 52 | 26 | 14 |
| Kitchen | 10 × 12 ft | 120 ft² | 130 | 65 | 33 |
| Bedroom | 12 × 12 ft | 144 ft² | 156 | 78 | 40 |
| Kitchen / dining | 12 × 16 ft | 192 ft² | 207 | 104 | 53 |
| Living room | 14 × 18 ft | 252 ft² | 272 | 137 | 69 |
1/8 in joints, 10% extra, rounded up. Typical sizes for illustration; measure your own room.
Grout and thinset for a tile floor
Grout fills the joints between tiles, so the amount depends on joint width, tile size and tile thickness: narrow joints and big tiles need little grout; small mosaic-like tiles with wide joints need a lot. Thinset is spread over the whole floor, so it depends on area and on the trowel notch.
grout volume = area × joint × (W + L) ÷ (W × L) × depth ÷ 12 · grout lb ≈ volume (ft³) × 105
thinset bags = area ÷ coverage per 50 lb bag (85 ft² with a 1/4 × 1/4 in trowel, 60 ft² with 1/4 × 3/8 in)
| Tile | Joint | Grout per 100 ft² (3/8 in deep) | Thinset trowel | Thinset per 100 ft² |
|---|---|---|---|---|
| 12 × 12 in | 1/8 in | 6.8 lb | 1/4 × 1/4 in | 2 × 50 lb |
| 12 × 24 in | 1/8 in | 5.1 lb | 1/4 × 3/8 in | 2 × 50 lb |
| 18 × 18 in | 3/16 in | 6.8 lb | 1/4 × 3/8 in | 2 × 50 lb |
| 24 × 24 in | 1/8 in | 3.4 lb | 1/4 × 3/8 in | 2 × 50 lb |
| 6 × 24 in | 1/8 in | 8.5 lb | 1/4 × 1/4 in | 2 × 50 lb |
| 3 × 6 in | 1/16 in | 10.3 lb | 1/4 × 1/4 in | 2 × 50 lb |
Grout weight assumes about 105 lb per cubic foot, typical for sanded grout; unsanded and epoxy grouts differ, and the coverage chart on your grout bag takes priority. Thinset coverage is the lower end of the manufacturer's range, because uneven floors and back-buttering large tiles use more.
Layout patterns and how much extra to buy
The pattern changes how many tiles end up cut at the walls. A straight grid wastes least; a diagonal layout turns every edge tile into a triangle; herringbone with plank tiles leaves angled offcuts along all four walls.
| Layout | Typical extra | 12×24 in tiles for 120 ft² |
|---|---|---|
| Straight | 10% | 65 |
| Brick / offset | 10% | 65 |
| Diagonal | 15% | 68 |
| Herringbone | 15% | 68 |
How to measure a floor for tile
- Split the floor into rectangles. Measure each rectangle wall to wall, including the space under freestanding fixtures and to the middle of door thresholds.
- Add the areas. Length × width for each rectangle, then add them up. The calculator does this for up to four areas.
- Choose tile size, joint and layout. The joint slightly increases what each tile covers; the layout sets the extra for cuts: about 10% straight, 15% diagonal or herringbone.
- Round up to whole tiles and boxes. Divide the area with extra by the coverage per tile, round up, then divide by tiles per box (or square feet per box) and round up again.
Area = Σ (length × width) · coverage = (W + joint) × (L + joint) ÷ 144 · tiles = ⌈ area × (1 + extra) ÷ coverage ⌉
Example: a 12×10 ft kitchen with a 5×4 ft nook is 120 + 20 = 140 ft². With 12×24 in tiles and 1/8 in joints each tile covers (12.125 × 24.125) ÷ 144 = 2.031 ft², so 140 × 1.10 ÷ 2.031 = 75.8, or 76 tiles.
Before you buy
- Check the lot number. Buy all boxes from the same production lot so the shade matches.
- Read square feet per box. It is printed on the carton and is the fastest way to turn area into boxes.
- Large-format tile needs a flat floor. Tiles 15 in and longer show lippage on uneven subfloors; plan for leveling compound.
- Keep spares. One box left over is cheap insurance for repairs.
Questions
How many floor tiles do I need for a 10x12 room?
120 ft². With 10% extra and 1/8 in joints that is 130 tiles at 12×12 in, 65 at 12×24 in or 33 at 24×24 in.
How many tiles for a 5x8 bathroom floor?
40 ft². That is 44 tiles at 12×12 in with 10% extra. Small rooms have a higher share of cut tiles, so many installers add 15% here: 46 tiles.
Should I tile under the vanity or kitchen cabinets?
Freestanding vanities and appliances usually sit on finished tile, so include that area. Built-in cabinets are often installed first and tiled around, which saves tile; measure only the exposed floor in that case.
Do I include the doorway?
Yes. Measure to the middle of the door threshold, where the tile meets the transition strip.
Why buy an extra box?
Tile is made in batches (lots) whose color can vary slightly. A spare box from the same lot lets you replace a cracked tile later with one that matches.
More tile calculators
Tile calculator
Quick tile and box count for one area.
Grout calculator
Pounds of grout by tile size and joint.
Thinset calculator
Bags of thinset by trowel size.
Sources: thinset coverage per 50 lb bag from Custom Building Products data for PremiumPlus thin-set (85–95 ft² with 1/4 × 1/4 in, 60–67 ft² with 1/4 × 3/8 in square notch). Waste allowances reflect common installer practice. Calculations last checked 2026-11.