# Floor tile calculator

> 8′ × 5′ bathroom: 19 tiles, 2 bags of thinset, 1 bag of grout and the backer board, sized to your tile. Backer, thinset, tile and grout sized to your tile — bathroom, kitchen or entry, with the toilet reset when there is one.

## What to buy (8′ × 5′ bathroom)

Every line shows the quantity to buy and how StudSheet got it: the spacing, the waste and the package size, so you can check it before the supply house or the quote.

| Buy | Material | How StudSheet counts it | What it is for |
|---|---|---|---|
| **19 tiles (38 sq ft)** | Floor tile (12×24, porcelain) | A grid of whole tiles over 5′ × 5′ 6″, plus one per offset row (30″ × 60″ tub footprint left out) = 17, + 2 spares for breakage and future repairs. Buy from one lot number. | Porcelain or ceramic. |
| **1 bag** | Large-format tile mortar, 50 lb (50 lb bag) | 27.5 sq ft ÷ 40 sq ft per bag with a ½″ × ½″ square notch trowel, +20% for back-buttering. | Thicker, non-slumping mortar for big tile. |
| **3 sheets** | Cement backer board ¼″ (3×5) (3×5 sheets) | 27.5 sq ft + 10% ÷ 15 sq ft per sheet. | Stable, water-tolerant base for tile over wood. |
| **1 bag** | Modified thinset mortar, 50 lb (50 lb bag) | Backer board is set in thinset (¼″ square notch, ~80 sq ft/bag), not laid dry. | Cement-based adhesive that bonds tile. |
| **≈135 screws** | Cement board screws 1¼″ | A screw every 8″ in each direction — about 45 per sheet. | Coated screws with ribbed heads. |
| **1 roll** | Alkali-resistant mesh tape 2″ (2″ × 150 ft) | Tape and thinset every backer seam. | For backer-board seams. |
| **1 × 10 lb bag** | Sanded grout (1/8″ joints) | Joint volume: (12+24)″ × 1/8″ wide × 3/8″ deep per tile ≈ 0.84 cu in per sq ft × 27.5 sq ft ≈ 1.7 lb with 15% extra. Sanded for joints ⅛″ and up. | For joints ⅛″ and wider. |
| **57 clips (1 × 100) + 1 set of wedges** | Tile leveling clips + wedges (clips (single use) + wedges) | 3 clips per tile × 19 tiles. Stops lippage on large tile. | Pull neighboring edges flush on large tile (no lippage). |
| **1** | Grout sealer (penetrating) | Cement grout stains; seal after it cures (see the grout bag). | Slows staining in cement grout. |
| **1 tube** | 100% silicone, color-matched (color-matched to grout) | The joint at walls and the tub is a movement joint — silicone, not grout. | Flexible movement joint at walls and the tub. |
| **1** | Threshold / transition (36″) | Finishes the edge at the bathroom door. | Finishes the tile edge at the doorway. |
| **1** | Wax ring (or wax-free seal) (standard) | Never reuse the old one. | Seals the toilet to the drain flange. |
| **1 set** | Closet bolts (brass) | New bolts; the old ones rarely come out clean. | Hold the toilet to the flange. |

### In Canada (2.44 m × 1.52 m bathroom)

Set to Canada, the Sheet works the job out again for Ontario: metric sizes, bag sizes, the frost depth and the code notes. It doesn't just convert feet to meters. The first lines:

- **19 tiles (3.5 m²), Floor tile:** A grid of whole tiles over 1.52 m × 1.68 m, plus one per offset row (762 mm × 1.52 m tub footprint left out) = 17, + 2 spares for breakage and future repairs. Buy from one lot number.
- **1 bag, Large-format tile mortar, 22.7 kg:** 2.6 m² ÷ 3.7 m² per bag with a 13 × 13 mm square notch trowel, +20% for back-buttering.
- **3 sheets, Cement backer board 6 mm (3×5):** 2.6 m² + 10% ÷ 1.4 m² per sheet.
- **1 bag, Modified thinset mortar, 22.7 kg:** Backer board is set in thinset (6 mm square notch, ~7.4 m²/bag), not laid dry.
- **≈135 screws, Cement board screws 32 mm:** A screw every 203 mm in each direction — about 45 per sheet.
- **1 roll, Alkali-resistant mesh tape 50 mm:** Tape and thinset every backer seam.

## The steps, in order

> **DIY OK: you can do this yourself with standard tools.** About 11–16 hours of work for this example.

1. Shut off the water, pull the toilet and stuff a rag in the drain. Remove the old floor down to the subfloor.
2. Screw down the subfloor and check flatness: ⅛″ in 10 ft for large tile.
3. Set ¼″ cement board in thinset, screws every 8″, gaps ⅛″; tape seams with alkali-resistant mesh and thinset.
4. Dry-lay from the doorway view: no slivers under half a tile at the door or along the tub. Keep the offset at ⅓ or less (long tile warps).
5. Mix thinset, let it slake 5–10 minutes, remix. Comb with the ½″ × ½″ square notch in straight lines; back-butter every tile; set leveling clips. Lift a tile now and then to check coverage.
6. Cut with the wet saw; notch around the flange with the grinder.
7. Wait 24 hours. Grout diagonally across the joints; clean the haze with a barely damp sponge.
8. Leave the wall and tub joint ungrouted and fill it with matching silicone.
9. Reset the toilet on a new wax ring, with the flange extender if the flange ends up below the tile. Seal the grout once it cures.

## Tools (30)

Must-have tools first, then the ones that help and the ones to rent for the day.

| Tool | Need | Why |
|---|---|---|
| **Notched trowel** | **Must have** | ½″ × ½″ square notch |
| **Margin trowel** | **Must have** | Narrow flat trowel for mixing and back-buttering. |
| **½″ drill + mixing paddle** | **Must have** | Thinset mixed by hand stays lumpy |
| **5-gal buckets (2)** | **Must have** | Mixing, rinsing, hauling. |
| **Grout float** | **Must have** | Rubber float that packs grout into joints. |
| **Grout sponges + 2 buckets** | **Must have** | Cleans haze. One bucket to rinse, one of clean water. |
| **4-ft level** | **Must have** | Checks plumb and level over a long span. |
| **Straightedge (6 ft)** | **Must have** | Dead-straight edge for cutting sheets and checking floor flatness. |
| **Chalk line** | **Must have** | Snaps a long straight line on floors, subfloors and ceilings. |
| **Tape measure (25 ft)** | **Must have** | The red boxes every 16″ on the blade are stud spacing. |
| **Speed square** | **Must have** | Triangle square for marking square and angled cuts on lumber. |
| **Carpenter's pencil** | **Must have** | Flat, doesn't roll away, marks rough lumber. |
| **Angle grinder + diamond blade** | **Must have** | Notches around the toilet flange |
| **Knee pads** | **Must have** | Flooring and tile are all knees. |
| **Rubber mallet** | **Must have** | Taps block, tile and planks into place without damage. |
| **Work gloves** | **Must have** | Thinset is caustic |
| **Safety glasses** | **Must have** | Every cut, every nail, every time. |
| **Hearing protection** | **Must have** | Saws and nailers are loud enough to damage hearing. |
| **Half-face respirator (P100)** | **Must have** | Silica dust from dry cuts |
| **Cement-board scoring knife** | **Must have** | Carbide tip: score, snap, done. |
| **Cordless drill/driver** | **Must have** | Drills holes, drives screws, mixes small batches. |
| **Oscillating multi-tool** | **Must have** | Undercut the door casing |
| **Utility knife + blades** | **Must have** | Scores drywall and vinyl plank, trims pad. Swap blades often. |
| **Putty knife** | **Must have** | Scrape off the old wax |
| **Screwdriver set** | **Must have** | Outlet covers, hardware, toilet bolts. |
| **Pry bar** | **Must have** | Old floor removal |
| **Floor scraper** | **Must have** | Removes old pad, staples and adhesive. |
| **Shop vac** | **Must have** | Drywall dust, grout, sawdust. |
| **Wet tile saw** | Rent | Clean cuts in porcelain and stone |
| **Tile snap cutter** | Good to have | Fast straight cuts, no water |

## Mistakes and how the math works

### Mistakes that cost a callback or a second trip

- **Grouting the change of plane:** Grout at walls and the tub cracks as the house moves. That joint gets flexible silicone.
- **Too small a trowel:** Big tile over thin ridges leaves hollow spots that crack when stepped on. ½″ × ½″ square notch here, plus back-buttering.
- **Forgetting the new floor height:** The floor rises about 1″. Plan the toilet flange and the door threshold before you start.

### What the calculator assumes

- Thinset per 50 lb bag: 80 sq ft (¼×¼), 60 (¼×⅜), 40 (½×½) — conservative values inside the Custom, MAPEI and LATICRETE data-sheet ranges. +20% for back-buttering large tile.
- Large-format = any edge ≥ 15″ (ANSI flatness rule: ⅛″ in 10 ft). Offset ≤ 33% when the offset side is over 18″.
- Grout: joint volume from tile size, joint width and tile thickness (3/8″), ≈ 0.065 lb per cu in, +15%.
- Sanded grout for joints ⅛″ and wider, unsanded below (manufacturers overlap at ⅛″).
- Deflection: L/360 for ceramic and porcelain, L/720 for natural stone (TCNA).
- A 30″ × 60″ tub along the short wall is left out.
- Tile count: whole pieces by rows × columns (a cut tile still uses a tile), +1 per offset row, +10% spares (13% for plank tile). Diagonal: area + 15%.
- Pre-1980s vinyl flooring and its adhesive can contain asbestos — test before removing.

## Code, permits and safety

The Sheet sets its code notes for the job's state or province. These are New Jersey's and Ontario's; the [code reference](https://studsheet.com/codes) has more. Always confirm with your building department.

- **Permits:** a job like this usually needs none, but towns set their own rules. Ask your building department if you're not sure.

## Questions

### What materials do I need to tile a bathroom floor?

For the worked example, a 8′ × 5′ bathroom, the Sheet counts 13 lines with waste included, starting with floor tile (19 tiles (38 sq ft)), large-format tile mortar, 50 lb (1 bag), cement backer board ¼″ (3×5) (3 sheets), modified thinset mortar, 50 lb (1 bag). Each line's math is in the table above. Put in your own sizes in the [floor tile calculator](https://app.studsheet.com/p/tile) and every line is counted again.

### How long does it take to tile a bathroom floor, and can I do it myself?

About 11 to 16 hours for the worked example, in 9 steps. StudSheet stamps it **DIY OK**: you can do this.

### What tools do I need to tile a bathroom floor?

30 in all. The must-haves start with notched trowel, margin trowel, ½″ drill + mixing paddle, 5-gal buckets (2), grout float, grout sponges + 2 buckets. On the Sheet you mark each one as owned, to buy or to rent.

## Ask about it

Stuck while you tile a bathroom floor? Ask in the [Floor tile group](https://studsheet.com/forum/floor-tile) of the StudSheet community with this Sheet attached. Homeowners who've done it and verified pros answer, and anyone can read it.

## More flooring & tile Sheets

- **[Tile for contractors](https://studsheet.com/trades/tile)**: run this takeoff at your own prices, send the estimate, and get it signed and the deposit paid.
- **[Carpet a room](https://studsheet.com/sheets/carpet)** (14′ × 12′ room): Tack strip, pad, seams and stretching — the full stretch-in install.
- **[Install vinyl plank flooring](https://studsheet.com/sheets/lvp)** (14′ × 12′ floor): Click-together LVP: boxes, trim, transitions and the gaps that matter.
- **[Hardwood and laminate floors](https://studsheet.com/sheets/woodfloor)** (14′ × 12′ floor): Install solid or engineered hardwood or laminate, or sand and refinish an old wood floor.
- **[Tile a kitchen backsplash](https://studsheet.com/sheets/backsplash)** (12′ of backsplash, 18″ tall): Tile, adhesive, grout, edge trim and outlet extenders for the wall between the counter and the cabinets, counted from the run and height.
- **[Tile a shower or tub surround](https://studsheet.com/sheets/shower)** (5′ tub surround, tiled to 7′): Backer board, waterproofing, tile, thinset and grout for a tub surround or a walk-in shower — every seam, corner and pipe sealed.
- **[Carpet stairs](https://studsheet.com/sheets/carpetstairs)** (13 steps, 3′ wide): Carpet, pad and tack strip cut step by step — waterfall or wrapped (Hollywood) — with the pile running down the stairs and the landing included.
- **[All 45 Sheets](https://studsheet.com/sheets)**, across 16 trades.
- **[Code reference](https://studsheet.com/codes):** frost depths, guard heights, stairs, retaining walls.