Drywall calculator

How the sheets are calculated

area to board = area × layers × (1 + waste ÷ 100) · board area = width × length ÷ 10,000 · sheets = area to board ÷ board area (rounded up)

Sheets are calculated on the net area you are boarding, multiplied by the number of layers and increased by the waste. Double boarding means double the sheets — not the same number rounded twice, which is the usual mistake when it is done in the head.

Take the board size off the pack: 120 × 200, 120 × 250, 120 × 260 and 120 × 300 cm are the usual ones, and the buttons above the fields only prefill those two always-editable fields. For an irregular surface, work the area out first in the area calculator and enter it in the “I know the area” mode.

Waste covers cutting around openings, corners and services, and the odd board damaged in handling. It starts at 10% and stays yours to change — a planning convention, not a standard. A wall full of openings and recesses uses more than a plain run of the same size.

Framing: how many studs and how much track

The number of vertical profiles (studs) is the number of spacings plus one. A 5 m wall at 60 cm centres has 5 ÷ 0.6 = 8.33, so 9 spacings — but 10 studs, because both the start and the end of the wall carry one. That “plus one” is the commonest error in a hand calculation and it always costs you, because it buys one profile too few.

Studs are not spliced: one stud runs floor to ceiling in a single piece. So a 4 m profile gives just one stud for a 2.6 m wall, with 1.4 m left over — while a 5.2 m profile gives two. Track at the floor and the ceiling, by contrast, IS butted end to end, so its sum is a plain division of twice the wall run by the length of one profile.

If the profile is shorter than the wall is high, the calculator says so outright instead of offering a number: not one whole stud comes out of it. Framing is calculated in wall mode only — a suspended ceiling has its own hanger and channel layout, which this calculator deliberately does not model.

Screws, compound and what is not estimated

The screws per m² and the joint-compound coverage have no default, because they depend on the board thickness, the stud spacing and the level of finish, and there is no figure we could cite a source for. The fields are empty on purpose: take the numbers from the system you are installing and from the compound bag. The calculator only multiplies and rounds them.

Compound is calculated on the NET finished face — never multiplied by the layers or the waste. You finish one visible surface however many boards are behind it, and offcuts are not jointed. Multiplying by layers would demand twice the compound on a double-boarded wall with exactly the same surface to skim.

Joint tape is not estimated. Its length depends on how the boards are laid out and how many butt joints there are, not on the area — so any metres-per-m² figure would be invented. The same goes for the suspended-ceiling grid: better no number than a wrong one.

Worked example: a 5 × 2.6 m wall

A 5 × 2.6 m wall is 13 m². In one layer with 10% waste you board 14.3 m². A 120 × 250 cm sheet is 3 m², so you need 14.3 ÷ 3 = 4.77, that is 5 sheets. In two layers it is 28.6 m² and 10 sheets.

Framing: at 60 cm centres you need 10 studs, which is 26 m of profile. Track comes to 2 × 5 = 10 m; at 3 m per piece that is 4 pieces. If the profiles are 4 m long, each yields one stud, so 10 pieces for the studs.

If the system's data gives 20 screws per m², that is 14.3 × 20 = 286 screws. If the bag says 1.2 kg/m², it is calculated on the net 13 m² and gives 15.6 kg — one 20 kg bag. If a sheet costs 18 KM, the boards come to 5 × 18 = 90 KM; the prices are an example, enter your own.