Plasterboard & fixings calculator

Enter your room size (or the wall and ceiling areas), choose a board and how it’s being fixed and finished, and we’ll work out the plasterboard, drywall screws, dot-and-dab adhesive, jointing tape and filler or skim plaster you need. Everything is rounded up to the bags, boxes and rolls we sell and priced live from the shop.

Building a new stud wall or ceiling frame? Use the drywall partition calculator or the MF ceiling calculator for the metal framing.

Your room

Each 1981 × 838mm (1.66m²).
Total area of other openings.

Boards

Fixing and finishing

Your materials

Call 03330 908479

Usage we’ve allowed
    Estimate only. Based on a simple rectangular room. It doesn’t include framing, beads, sealant or insulation, and actual usage of adhesive, filler and plaster depends on the background, the flatness of the wall and the skill of the fixer. Check the list against the manufacturer’s guidance or with your plasterer, and call us on 03330 908479 if you’d like us to look it over.

    How we calculate

    • Area: walls = 2 × (length + width) × height, less doors (1.66m² each) and other openings. Ceiling = length × width.
    • Boards: total area × layers, plus waste, divided by the board area and rounded up.
    • Screws: British Gypsum guidance is screw centres of 300mm on walls and 230mm on ceilings (150mm at board ends). We count a line of screws on each stud or joist the board crosses: studs at 600mm centres for 1200mm-wide boards (450mm for 900mm boards), joists or MF channels at 450mm. Screw length is the board thickness plus at least 10mm into metal or 25mm into timber (British Gypsum), fine thread for metal and coarse thread for timber.
    • Dot and dab: about two 2400 × 1200mm boards (5.76m²) per 25kg bag of Gyproc DriWall Adhesive, as British Gypsum states for normal use. Uneven walls use more.
    • Tape and joint: joint length is estimated as one long edge plus one short edge per board on the face layer. Paper tape comes in 150m rolls. Wondertex’s published coverage is about 100 linear metres per 12.5kg bag of Filler and about 150 linear metres per 25kg bag of Finishing Compound (two feathered coats).
    • Skim: Thistle MultiFinish and BoardFinish cover approximately 10m² per 25kg bag at 2mm (British Gypsum), with scrim tape over the joints.
    • The waste allowance is added to the area first and every item is worked out from that, then rounded up to whole boards, boxes, rolls or bags.

    Questions

    Tapered edge or square edge?

    Tapered edge boards have a shallow recess along the long edges so the joints can be taped and filled flush for decoration without plastering. Square edge boards are normally skimmed with finish plaster. Either can be skimmed.

    12.5mm or 15mm?

    12.5mm is the everyday board for walls and ceilings. 15mm is stiffer, a little better for sound and is often used in fire-rated or acoustic systems, so check the specification for your wall or ceiling.

    Which screws do I need?

    Fine thread screws for metal studs and MF ceilings, coarse thread for timber. The screw should go at least 10mm into metal or 25mm into timber, so a 12.5mm board needs a 25mm screw into metal and about 38mm into timber. The calculator picks the length for you.

    Is there a minimum order?

    Yes. Plasterboard, fixings and plaster have a £400 ex VAT minimum order. Delivery is free to England & Wales on orders over £500 ex VAT and £50 ex VAT below that.

    Can I dot and dab two layers?

    Only the first layer is bonded with adhesive. This calculator handles dot and dab for a single layer. For two layers or thermal laminate boards, call us and we’ll work out the fixings with you.