Boards & Drylining

Plasterboard calculator

Estimate whole plasterboard boards from measured wall and ceiling faces, named openings and the coverage of the board you have chosen.

Start with what you can measure. For a product figure, use the label or product page. Your practical estimate appears first; the technical detail sits below it.

01Tell us what you can measure

Add your measurements, then check the steps before you buy.

Units

Walls and ceilings to cover

Add every wall or ceiling face you measured. Start with length × width or height; use the already-measured-area option only when you have it. Add a door, window or other opening only to the surface it reduces.

Wall or ceiling surface01

Surface name optionalWhat are you covering?How was this surface measured?

Wall width m

Wall height m

Include this surface in the estimateExcluded surfaces stay visible but do not affect the board estimate.

Chosen board and extra allowance

Use the size or coverage printed for one board you have already chosen.

How do you know the board coverage?

Board length mFrom the board label.

Board width mFrom the board label.

Extra allowance

Choose 0% for a minimum coverage estimate. Otherwise enter your own figure for cuts and offcuts.

Extra allowance %

Board labels may use mm: 2400 mm = 2.4 m; 1200 mm = 1.2 m. Use your label’s actual values.

Your estimate updates as you type. Use Calculate estimate for a clear check of anything still needed.

02What to buy

Add a wall or ceiling surface, board details and your allowance to see an estimate.

Add the wall and ceiling surfaces you measured, named openings, the dimensions or stated coverage for one chosen board, and the allowance you want to use. Then you can see the whole-board estimate and each step.

What this does not cover: Minimum area-coverage estimate only — not a cut plan. Cuts, openings and room shape can mean more boards are needed. It does not choose or assess board type, thickness, performance, suitability, framing, fixing, joints, installation, compliance or safety.

See the working

How the estimate works

Follow the short steps from your measurements to the final rounded quantity.

Add your measurements above to see how we worked it out.

Where the numbers come from

A quick guide to this estimate.

You enterMeasured wall and ceiling surfaces, linked doors/windows/openings, board details and the allowance you choose.
You can change:The named wall and ceiling measurements, linked openings and extra allowance you choose (including zero).
From the product details you enterThe length and width, or stated coverage, for the one board you have chosen.
Worked out hereWe total only the included walls and ceilings after their linked openings, add your allowance, divide by the board coverage and round up to whole boards.

Measuring tips

What to measure

Add each wall or ceiling face you intend to cover. Start with length × width or height, or use an area you already know. Add every door, window or other clear opening to the surface it reduces. Then use the dimensions or stated coverage for one board you have already chosen.

Measure the finished surface or dimensions used by this tool. Keep a note of the values you enter.

Worked example

See it in practice

A 3 m × 2.4 m wall and a 3 m × 2.4 m ceiling have 14.4 m² together. Taking away a 0.9 m × 2 m door leaves 12.6 m². With no extra allowance and a chosen board covering 2.88 m², that is 4.375 boards and rounds up to 5 whole boards, covering 14.4 m².

Keep a noteWrite down the product coverage, pack size or other product detail you used, so you can check it later.

Before you buy

Three quick checks

01
Keep each wall or ceiling face separate so you can recheck it.
02
Deduct only clear named openings, linked to the surface they reduce.
03
Use the dimensions or stated coverage for the exact board you have chosen, then check cuts and room shape before buying.

Quick answers

Useful to know

Should I deduct doors and windows?

Add any clear door, window or other opening you want to take away, linked to the wall or ceiling it reduces. The calculator checks that openings do not exceed that measured surface.

What board figure should I enter?

Use either the length and width printed for one board you have already chosen, or its stated coverage if that is what the product details give you. This calculator does not assume a generic board size.

Why is the whole-board number higher than the exact number?

Boards are counted as whole boards, so the exact coverage requirement is rounded up. Rounding surplus is coverage created by that rounding; it does not show whether offcuts will fit or be usable.

Does this tell me how to cut or choose plasterboard?

No. This is a minimum area-coverage estimate, not a cut plan. Cuts, openings and room shape can mean more boards are needed. It does not choose a board type, thickness, performance, suitability, framing, fixing, joints or installation method.

Method and checks

How this estimate is put together.

Calculation checked

Last checked 19 October 2026 · review again by 19 October 2027. The method version is available in the detail below.

The calculation steps and rounding are shown and have been checked. Before buying, check the coverage, pack size or other product detail you entered.

Keep in mind: plasterboard purchase-quantity estimate only; not board selection, suitability or installation advice. This remains a planning estimate, not a design or approval.

Details that can vary: No universal board size, board coverage or allowance is supplied. The estimate does not claim a board will fit a particular layout.

Check the product details: The length and width, or stated coverage, for the one board you have chosen. Calculator.Shop does not choose or supply these figures.

See sources, values you can change and method history

Sources for this method

Calculating the area and the perimeterMathplanet / Mattecentrum · mathematical definition · Public reference, accessed 17 October 2026Supports: Rectangle area (length × width) where a Calculator.Shop tool asks for a measured section. Pack, roll or board coverage and any extra allowance are values the visitor enters.

Values you can change

The named wall and ceiling measurements, linked openings and extra allowance you choose (including zero).

What we check

The stated calculation steps, rounding and limits of this estimate.

When we check it again

Before the formula, whole-board rounding or measurement-and-coverage method changes; Before board-detail, allowance or linked-opening wording changes; When the no-cut-plan or board-selection safety boundary changes.

Method history

v1.0 · 2026-10-19First Plasterboard Calculator method: visitor-measured surfaces, linked openings, visitor-entered board details and transparent whole-board rounding.

See how we verify calculations