PickGlobeTile calculator
Enter the area, tile size and layout to see how many tiles to buy.
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- Check the coverage, roll size or box size on the product label: it beats any typical figure.
- We round up to whole cans, rolls and tiles, and add the extra makers recommend for cuts and spares.
- Doors and windows, trim and odd shapes change the result, so measure your own room.
How we calculate
Paint. Wall area = room perimeter x wall height, minus 20 sq ft (1.9 m2) per door and 15 sq ft (1.4 m2) per window, plus the ceiling if you choose it. Paint needed = area x coats / coverage. Coverage defaults to 350 sq ft per gallon (10 m2 per litre), the cautious end of the makers' figures, and you can enter the figure from your tin. We then pick the whole cans that cover the need with the least paint left over.
Wallpaper. Drop length = wall height + trim allowance + pattern repeat. Drops per roll = roll length / drop length, whole drops only. Drops needed = perimeter / roll width, rounded up. Rolls = drops needed / drops per roll, rounded up, plus a spare roll or 10%, whichever is more. A pattern repeat is added in full to every drop, the cautious method: with a pattern that matches, some drops need less than a full repeat, so you may have a roll left over.
Tile. Tiles = area / (tile size plus the grout joint), plus 10 to 20% extra for cuts and spares depending on the layout, rounded up.
Worked examples:
- A 14 x 12 ft room with 8 ft walls, one door and two windows, two coats: walls are 2 x (14 + 12) x 8 = 416 sq ft, minus 20 + 30 = 366 sq ft; 366 x 2 / 350 = 2.09 gallons, so 2 gallons and a quart (2.25 gal).
- A 4.3 x 3.7 m room with 2.4 m walls, one door and two windows, two coats at 10 m2 per litre: walls 38.4 m2, minus 1.9 + 2.8 = 33.7 m2; 33.7 x 2 / 10 = 6.7 litres, so one 5 L and two 1 L cans (7 L).
- Wallpaper for the same room on 53 cm x 10 m rolls, plain paper, 10 cm trim: the drop is 2.5 m, so 4 drops per roll; the 16 m perimeter needs 31 drops, which is 8 rolls, and with a spare you buy 9. With a 64 cm repeat the drop is 3.14 m, so 3 drops per roll and 11 rolls (13 with the spare).
- Tiles for the same floor with 300 x 300 mm tiles and a 3 mm joint on a straight lay: 15.9 m2 / 0.0918 m2 is 173.3, rounded up to 174 tiles; plus 10% is 191.4, so 192 tiles.
What is firm and what is not: the coverage figures are from the makers' own pages (Sherwin-Williams, Benjamin Moore, Dulux UK and Australia, Resene), but "up to" numbers are best case and Behr's pages could not be read, so the rough-surface preset and the door and window allowances come from a search snippet or from Sherwin-Williams' wallpaper guide. The 10 and 30 cm trim allowances for wallpaper are from retailer snippets. Tile overage is from Tile Mountain and Cle Tile; we found no trade-body figure and do not attribute one. Adhesive, grout and trim paint are not included.
The rates we use
| Item | Rule |
|---|---|
| Typical coverage | US makers state about 350 to 400 sq ft per gallon for one coat (Sherwin-Williams) and 400 to 450 (Benjamin Moore Regal Select). We default to the cautious 350. In metric, makers state about 11 m2 per litre (Resene) and up to 14 (Dulux UK Matt) or about 16 (Dulux Australia); we default to 10 m2 per litre. "Up to" figures are best case. |
| Rough or porous walls | Rough, textured, bare or new absorbent surfaces use more paint (Dulux, Resene, Benjamin Moore). The rough preset (250 sq ft per gallon, 6.5 m2 per litre) follows the low end of Behr's range, which we saw only in a search snippet, so treat it as a rule of thumb. |
| Use your tin | Several makers say to use the figure on the tin. Choose "My tin says" and enter it. |
| Doors and windows | We take off 20 sq ft (1.9 m2) per door and 15 sq ft (1.4 m2) per window, figures we saw in a Behr snippet; Sherwin-Williams uses 20 sq ft for each door or window. Dulux and Resene say to measure each opening, so adjust if yours are unusual. |
| Coats and colour change | Two coats is usual. A strong or dark-to-light colour change may need more (Dulux). |
| Can sizes | US cans: quart, gallon, 5 gallon. UK cans: 1, 2.5, 5, 10 litre (Dulux). We round up to whole cans and check Australian can sizes in your store. |
Checked on 27 October 2026.
| Item | Rule |
|---|---|
| Roll sizes | UK and Europe: about 52 to 53 cm wide by 10 to 10.05 m long (Dunelm, Farrow & Ball). US double roll: 20.5 in by 33 ft, about 56 sq ft (Brewster); some 27 in rolls exist. |
| The drop method | Drop length = wall height + a trim allowance + one pattern repeat. Drops per roll = roll length divided by drop length, whole drops only. Drops needed = room perimeter divided by roll width, rounded up. Rolls = drops needed divided by drops per roll, rounded up. |
| Pattern repeat | A repeat means more paper is lost per drop, so a large repeat can cut a roll to 2 or 3 drops on a 2.4 m wall (Dunelm, Farrow & Ball). |
| Openings | We do not deduct doors and windows, which leaves a small surplus (Graham & Brown). |
| Spare | Graham & Brown advise about 10% extra; Farrow & Ball and Sherwin-Williams say to buy an extra roll, also so later batches match. We add whichever is larger. Trim allowance figures (10 to 30 cm) are from retailer snippets we could not read in full: use 10 cm for a tidy wall and 30 cm to be safe. |
Checked on 27 October 2026.
| Item | Rule |
|---|---|
| Straight lay | Tile Mountain advises 10% extra for a straight layout, and Topps Tiles and Daltile list 10% in their own calculators and listings (the last two we saw in snippets). |
| Brick bond | 10 to 15% (Tile Mountain). We use 15%. |
| Diagonal and herringbone | 15% (Tile Mountain). Some blogs go higher for herringbone, so use 20% if the pattern is intricate. |
| Large tiles in small rooms | 15 to 20% (Tile Mountain), because big offcuts cannot be reused. We use 20%. |
| Why extra | Cuts at the edges, breakage in transit and on site, and spares for future repairs, since later batches may not match the shade (Tile Mountain, Cle Tile). We could not find a Tile Council of North America figure, so we do not attribute any percentage to it. We left out adhesive and grout amounts: they are on each product's data sheet. |
Checked on 27 October 2026.
Sources and last checked
- Paint: how much covers what, checked 27 October 2026: Sherwin-Williams paint calculator page (read 2026-10-27); Benjamin Moore Regal Select Interior Satin/Pearl (US) product page (read 2026-10-27); Benjamin Moore Regal Select Interior Flat (Canada) product page (read 2026-10-27); Dulux UK: how much paint do you need (read 2026-10-27); Dulux Matt (UK) product page (read 2026-10-27); Dulux Australia paint calculator (read 2026-10-27); Resene paint calculator (read 2026-10-27); Benjamin Moore paint calculator (read 2026-10-27); Sherwin-Williams: how to estimate wallpaper (read 2026-10-27)
- Wallpaper: rolls and drops, checked 27 October 2026: Dunelm: how to measure wallpaper (read 2026-10-27); Farrow & Ball: calculating wallpaper quantities (US page) (read 2026-10-27); Graham & Brown: how to measure for wallpaper (UK and AU pages) (read 2026-10-27); Brewster Westley Grey Plaid product page (read 2026-10-27); Sherwin-Williams: how to estimate wallpaper (read 2026-10-27)
- Tile: overage, checked 27 October 2026: Tile Mountain: how many tiles do I need (read 2026-10-27); Cle Tile help: why the calculator adds 15% (read 2026-10-27)
Quantities are estimates. Coverage, roll and box sizes vary by product, so check the label and buy a little extra. Not a substitute for a contractor's measurement. Read more: Paint and indoor air: what the EPA says.