Solve backwards
How much floor tile will my bags of thinset set?
- 3 bagsThe example worked below
- Thinset & Tile Adhesive CalculatorEvery figure is its own
You have
How much thinset?
Worked by the Thinset & Tile Adhesive Calculator at the settings below.
The settings it uses
- Trowel notch
- 3/8 in square — up to 24 in tile (~1.02 lb/sq ft)
- Back-buttering
- No
- Bag size
- 50 lb
What it will do
146 sq ft of tiling
13.6 m²
One tiled floor. Enough for a tiled floor about 12.1 × 12.1 ft.
Or several. About 1 tiled floor of the size the Thinset & Tile Adhesive Calculator opens on: a tiled floor about 11.4 × 11.4 ft.
Check it forwards
- Area to tile
- 146 sq ft
- It asks for
- 3 bags
- You have
- 3 bags
The Thinset & Tile Adhesive Calculator asks for 3 bags at that size, and 4 bags one step larger.
If you had more, or less
Around your amount
Each worked by the Thinset & Tile Adhesive Calculator at the same settings.
Half
2 bags
97.6 sq ft
a tiled floor about 9.9 × 9.9 ft
Yours
3 bags
146 sq ft
a tiled floor about 12.1 × 12.1 ft
Half as much again
5 bags
244 sq ft
a tiled floor about 15.6 × 15.6 ft
Double
6 bags
293 sq ft
a tiled floor about 17.1 × 17.1 ft
Common amounts
What each amount of thinset covers
The sizes it is usually sold in, each worked by the Thinset & Tile Adhesive Calculator at the settings above.
| You have | It covers | As one tiled floor | Average tiled floors |
|---|---|---|---|
| 1 bag | 48.8 sq ft(4.54 m²) | a tiled floor about 7 × 7 ft | under 1 |
| 2 bags | 97.6 sq ft(9.07 m²) | a tiled floor about 9.9 × 9.9 ft | under 1 |
| 3 bags | 146 sq ft(13.6 m²) | a tiled floor about 12.1 × 12.1 ft | 1 |
| 5 bags | 244 sq ft(22.7 m²) | a tiled floor about 15.6 × 15.6 ft | 1 |
| 10 bags | 488 sq ft(45.4 m²) | a tiled floor about 22.1 × 22.1 ft | 3 |
The notch sets the consumption
The trowel notch, not the tile, decides how much adhesive stays on the floor. The calculator opens at a 10 mm notch, about 5 kg per square metre (roughly a pound per square foot), for medium and large floor tile. A smaller notch under a large tile is the commonest cause of hollow spots and later cracking.
Back-buttering adds about a third
A skim on the back of each tile, on top of the combed bed, is needed in practice on large-format tile and in wet areas, where TCNA calls for 95 per cent coverage against 80 for dry interiors. It adds roughly a third to the adhesive, so the same bags set about three-quarters of the floor shown here.
A dip is filled with adhesive
An uneven substrate consumes considerably more than these figures, because every hollow is made up in adhesive. Levelling first is cheaper and performs better. A part-used bag of thinset does not keep long in a damp store, so buy whole bags with a little over rather than coming back mid-floor.
How the answer is worked
Nothing here is a second formula. The Thinset & Tile Adhesive Calculator runs forwards — a size in, a quantity out — and this page grows its own starting tiled floor in proportion until the quantity it asks for is what you have. Where it rounds up to whole containers, the answer is the largest size before the next one would be needed.
Where the calculator adds an allowance for cuts or breakage when you order, the same allowance comes off here, because it is the same calculator: a stack you already own finishes less than its face value. Where it adds none, neither does this page — the settings beside the answer say which.
Thinset & Tile Adhesive Calculator
runs it forwardsWork out the adhesive a tiling job needs from the trowel notch, which is what actually sets the coverage.
Work out what to buy insteadSolve backwards
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Solve backwards
Start from what is already in the yard
Paint, sheets, rolls, bags and pieces, each read the other way by the calculator that orders it.
The calculator's own figures
Nothing is estimated twice: the page runs the same calculator you would order with.
The largest size that fits
Where a calculator rounds up to whole containers, the answer stops before the next one.
Both unit systems
Gallons and litres, square feet and square metres, side by side.
Frequently asked questions
- How much tiling does 3 bags of thinset cover?
- At the Thinset & Tile Adhesive Calculator's own settings, 146 sq ft (13.6 m²) — a tiled floor about 12.1 × 12.1 ft. That is about 1 tiled floor of the size the calculator opens on: a tiled floor about 11.4 × 11.4 ft. Every figure follows the settings, which you can change in the calculator.
- How many square feet does a 50 lb bag of thinset cover?
- With a 10 mm (3/8 inch) notch, about 45 to 50 square feet (4.5 m²); with the smaller notch used for wall tile, noticeably more. Back-buttering large tiles adds about a third to the adhesive. The notch and the substrate move coverage more than the brand does.
- What size trowel notch should I use for floor tile?
- The notch rises with tile size and with how uneven the substrate is. The adhesive's data sheet names a notch for each tile size, and the notch must leave full contact under the tile — lift a tile after setting to check the back is fully covered.
- Do I need to back-butter floor tiles?
- On large-format tile and anything in a wet area, generally yes: it is the reliable way to reach the 95 per cent coverage TCNA requires in wet and exterior areas. On small tile in a dry room, a combed bed with the right notch usually reaches the 80 per cent required there.