Plasterboard Calculator

Updated October 2026

Quick answer: A 2400 × 1200mm plasterboard covers 2.88m². For 24m² with 10% cutting waste, calculate 24 × 1.10 ÷ 2.88 = 9.17 and buy ten sheets. Add screws and joint tape, then budget separately for adhesive if dot-and-dabbing, skim or joint filler, delivery and any specialist boards.

Measure the area before counting sheets

Measure each wall's length and finished height in metres, multiply them and add the results. Calculate the ceiling separately as length × width. A 4m × 3m room at 2.4m high has 14 × 2.4 = 33.6m² of gross wall plus a 12m² ceiling. A partition boarded on both faces needs both sides counted; a double-layer system doubles the relevant board area again.

Subtract large openings where complete sheets are saved, but retain allowance for window reveals, door heads and awkward cuts. Small sockets rarely save useful board. Drawing the sheet layout can reduce joints, expose unsupported edges and help choose a size that passes safely through doors and loft hatches.

The calculator offers the first two sizes. Figures in the table are area equivalents: always round the final project quantity up to whole sheets. Smaller boards are easier to move through tight access but create more joints and may cost more per square metre. Larger boards reduce joints only where the framing and handling arrangements support their use.

Choose the board for the construction

Thickness and board type are independent of area. Standard 12.5mm board is common in domestic work, but acoustic, moisture-resistant, fire-resistant and insulated boards are different specifications. A coloured face alone does not define a complete compliant wall. Stud spacing, layers, fixings and joint treatment form part of the system.

Moisture-resistant board is not a substitute for an appropriate waterproofing system in a shower. Ceilings also need the correct board and support spacing for the span. Check the specified construction before buying the cheapest sheet, especially where fire separation or sound performance matters.

Worked example: a 24m² wall project

1. Measured board area is 24m².
2. Allow 10% waste: 24 × 1.10 = 26.4m².
3. Standard sheets cover 2.88m²: 26.4 ÷ 2.88 = 9.17, rounded up to ten sheets.
4. At the example £9 per sheet, board cost is £90.
5. The calculator allows one screw box at £6 and one scrim roll at £4, producing £100 for its included materials.

At 1800 × 900mm, divide the same 26.4m² by 1.62: 16.30, rounded up to 17 boards. Change the price per board when switching size; £9 is an input example, not a claim that every board has the same price. The calculator's accessories are coarse purchase allowances, not an installation fixing schedule.

Screws, adhesive and scrim estimates

The tool buys one screw box, described as approximately 1,000 screws, for each group of up to 25 sheets, with a minimum of one. It allows one approximately 90m scrim roll per 40m² of waste-adjusted area. These simple rules help price packs; actual screw spacing and tape lengths come from the chosen system and drawn layout.

For dot-and-dab, 24m² at 4m² per bag needs six bags before handling losses. Adding 10% gives 26.4 ÷ 4 = 6.6, or seven bags. At an illustrative £14 per bag, that adds £98, which the calculator does not include. Adhesive fixing is suitable only for compatible sound backgrounds and specified details; it does not replace a ceiling support system.

Typical UK prices and finishing costs

For October 2026 planning, standard 2400 × 1200mm board may fall around £9–£16 per sheet, board adhesive around £12–£20 per 25kg bag, and a scrim roll around £4–£10. These are typical supply-only ranges, not quotes. Specialist boards, small screw boxes and delivery charges vary substantially; update each input from the actual pack you intend to buy.

Boarding is not the finished wall. Jointing compound, corner beads, skim plaster, sanding, primer and decoration sit outside the displayed total. Large sheets also require safe handling and dry storage: damp or damaged boards can turn a small saving into wasted material. Arrange support or lifting equipment for overhead work.

Use the calculator above for whole-sheet quantities. For the next stage, see how much plastering costs. For sequencing boards, skim and decoration, read the best order to decorate a room. This keeps the board order separate from the cost and drying time of the completed finish.

Frequently asked questions