Plasterboard calculator: sheets, fixings and compound

How it works

Add each rectangular wall or ceiling, choose the locally sourced board, enter the total area of openings and set a cutting allowance. The sheet count uses net area divided by sheet area. It is an area-based estimate, not a board-by-board cut plan.

For simple rectangular surfaces, screw lines use the selected manufacturer framing and fixing schedule. Tape follows an estimated full-sheet grid. The compound quantity uses the published jointing-compound rates, it is not a full-surface skim estimate.

Formula

• Estimate sheets

  Net area = wall and ceiling area − opening area Order area = net area × (1 + waste %) Sheets = ceil(order area ÷ selected sheet area)

  The result rounds the area-based sheet estimate up to whole boards.

• Estimate accessories

  Tape = full-sheet grid joint length Fixings = supported fixing runs × fixings per run at the cited maximum spacing Beads = ceil(measured external-corner length ÷ selected stock length)

  The accessory estimate assumes supported sheet edges and a simple rectangular layout. Opening edges and offcut reuse are not modeled.

• Estimate jointing compound

  20 kg buckets = ceil(order area × (24 + 8) kg per 100 m² ÷ 20 kg)

  This uses the selected compound for its published tape, second-coat and topping coverage. It is a jointing system, not generic skim plaster.

Worked example

1. 1

   Enter one wall

   Wall = 3.6 m × 2.4 m = 8.64 m² Selected board = 1.2 m × 2.4 m = 2.88 m²

   This example has no openings and no cutting allowance.

2. 2

   Count boards and tape

   ceil(8.64 ÷ 2.88) = 3 sheets Two vertical joints × 2.4 m = 4.8 m of tape

   The simple grid uses three full-width boards with no offcut reuse.

3. 3

   Estimate fixings and finish

   63 wall screws 1 × 20 kg buckets of All-Coat MAX jointing compound

   The screw count uses 600 mm framing and the cited 400 mm wall centres. The compound pack count follows the product coverage rates.

Assumptions and limits

The selected sheet and accessory data are specific manufacturer examples. Availability and system requirements vary. Confirm board suitability, framing, fixing schedule and finishing instructions for your project before ordering.

Openings reduce the board and finish area, but their position and perimeter are not modeled. The tape and fixing estimates therefore use the uncut rectangular surface grid and do not add fasteners around openings. Include extra cutting waste and check opening framing and jointing separately.

The local manufacturer guide varies by wall or ceiling, board, framing, wind category and tile loading. This estimate uses the listed internal non-tiled wall schedule and interior N1/N2 ceiling schedule. Confirm the applicable schedule, the selected ceiling board requires no more than 450 mm joist centres.

Frequently asked questions