Plasterboard Quantity Calculator

To work out how many sheets you need, add up the wall and ceiling area you are boarding, divide by the coverage of one sheet, and round up with a margin for cuts. A standard plasterboard sheet covers 2.88 m², so a large room quickly runs to a stack of boards once you account for offcuts around windows, doors, and reveals.

This estimator turns that rule into an order list. Enter the wall area and ceiling area you plan to dry-line, choose your board size, and set a waste margin. It returns the sheet count plus the consumables that go with them, and a supply cost range so you can sanity-check a merchant quote before you place the order.

How the sheet count is worked out

The maths is simple once you have the two areas. Total boarded area divided by 2.88 m² gives a raw sheet count, then the waste margin lifts it to a realistic order. The default margin covers the cuts you lose around openings and the offcuts too small to reuse. Rooms with lots of angles, reveals, or short runs waste more, so nudge the margin up for those.

Board size changes the count. The standard sheet is 2400 x 1200 mm, which suits normal room heights and is the easiest to buy and handle. Longer 3000mm boards reduce the number of horizontal joints in a tall room, and fewer joints means less tape, less filling, and fewer lines that can crack later.

Weight is worth planning for. A standard sheet weighs about 24 kg, which is fine solo on a wall but awkward and unsafe overhead. Ceiling boarding is a two-person job, or a one-person job with a ratchet board lifter.

Screws, tape, and compound

Boards are only part of the order. The calculator also estimates the drywall screws that fix the sheets to the studs or joists, the scrim tape that reinforces every joint, and the jointing compound that fills them. You do not need to price these separately: the tool counts them from your boarded area and folds them into the supply total, so the number you see is the full material spend rather than just the boards.

Board type: standard or moisture-resistant

Most of an extension takes standard ivory board. In a kitchen, use moisture-resistant board in the splash zones where humidity and the odd spill are a fact of life. Both types are ordered the same way and both take the same 2-3mm skim coat of multi-finish plaster, so switching board type in a wet area changes the spec, not the sheet count. Check your architect's specification for where each type is required.

A worked example

Say you are boarding 40m² of new wall and a 30m² ceiling, giving 70m² to cover. Divide that by the 2.88 m² a standard sheet covers, round up, and add the waste margin: the calculator above does exactly this and returns the sheet count and consumables in one pass. Multiply the sheet count by the £9 – £13 a standard 12.5mm board costs and you have the board bill, with screws, tape, and compound added on top.

That supply figure is only the material side. If you would rather a plasterer supply and fix the boards and skim them, budget around £18 – £30 per m²; a skim coat alone over boards you have fixed yourself runs around £15 – £25 per m². Doing the boarding yourself and paying only for the skim is a common split, and the sheet count from this calculator is the number you hand the merchant either way. See plastering for how the boarding and skim sequence fits into the rest of second fix.