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Internal · tiles · adhesive · grout
How many tiles, and how much adhesive and grout?
Tiles with a cutting allowance, adhesive by bed depth and grout by the actual joint volume — not the one-kilo-a-metre guess on the back of the bag.
Measure it
Every box has its own unit next to it.
Change the unit beside any box and the number converts. The (i) beside each question says what the box wants and where the figure usually comes from. Anything marked per cent is a percentage of the quantity above it.
Check the rates
Rates and assumptions used
These are the figures the calculator works to. Change any of them and the order list updates — your merchant’s pack sizes and your own waste allowances beat the defaults every time.
Order list
The orange figure is the one you order to. Highlighted rows are the other numbers you order to. The small print under each row is the sum that produced it, so you can check it against your own take-off. Amber rows are warnings, not quantities.
How this one works
- Tiles =
area ÷ tile area × (1 + cutting %) - Adhesive =
area × 1.5 kg per m² per mm of bed - Grout kg/m² =
((L + W) ÷ (L × W)) × joint width × tile thickness × 1.6
The figures the calculator works to. Every one can be changed in step 2, and your merchant’s pack sizes and your own waste allowances beat these defaults every time.
| Rate | Default | Why |
|---|---|---|
| Adhesive | 1.5 kg/m²/mm | Per square metre per millimetre of bed depth. |
| Adhesive bag | 20 kg | |
| Grout density | 1.6 kg/L | |
| Tiles per box | 8 no. | Check the actual box — it varies with size. |
| Grout bag | 5 kg | |
| Primer coverage | 10 m²/L |
A worked example
With the defaults the page opens on:
- How much area to tile? 12 square metres
- How long is a tile? 600 millimetres
- How wide is a tile? 300 millimetres
- How thick is a tile? 9 millimetres
- How wide are the joints? 3 millimetres
- How much spare for cuts? 10 per cent
- How thick a bed of adhesive? 3 mm — flat wall
Tiles
- Tile size: 0.18 m² — 600 × 300 mm
- Cutting waste: 10 %
- Tiles: 74 no. — area ÷ tile area, +10%
- Boxes: 10 boxes — at 8 a box
- Trim / edging: 3 × 2.5 m — estimate — count your exposed edges
Adhesive & grout
- Adhesive: 54 kg — at 3 mm bed
- Adhesive bags: 3 × 20 kg — 54 kg ÷ 20 kg, rounded up
- Grout: 2.6 kg — joint volume × 1.6 kg/L
- Grout bags: 1 × 5 kg — 2.6 kg ÷ 5 kg, rounded up
- Primer: 2 litres
- Spacers: 1 × 100 packs — 74 tiles × 1.2 spacers each ÷ 100, rounded up
Change any figure above and every line recalculates; the small print under each row is the sum that produced it.
Questions people ask
How many tiles do I need?
Area ÷ tile area × cutting waste. 12 m² in 600 × 300 tiles at 10% needs 74 tiles - about 10 boxes of 8.
How much grout do I need?
Not the one-kilo-a-metre guess on the bag. The calculator works the actual joint volume: ((L + W) ÷ (L × W)) × joint width × tile thickness × 1.6 kg/L. Narrow joints on big tiles use far less than that guess.
How much adhesive?
1.5 kg per square metre per millimetre of bed: 3 mm for a flat wall, 6 mm for a floor, 10 mm for uneven backgrounds or large format tiles, which also need back-buttering.
How much cutting waste?
10% on a square lay, 15% with a diagonal lay or lots of cuts.
Calculators for the same job
Doing this for a whole job rather than one wall? SiteLedger keeps the valuations, supplier statements, invoices and variations against the project they belong to.
Read before you order. These work out quantities, not structural design — spans, lintels, rebar and foundation depths need an engineer and Building Control sign-off. Waste allowances are defaults, not promises: awkward cuts, long runs and bad weather all eat more than 5%. Where a merchant sells whole packs, the figure is rounded up to whole packs.