How many bricks per m²?

With a standard brick (24 × 11.5 cm) and a 1 cm joint, you get approx. 38–40 bricks per m² for a half-brick wall. For a full-brick wall, multiply by 2.

How do I deduct windows and doors?

Subtract the area of each opening (width × height) from the total before entering it in the calculator. Standard door: 0.9 × 2.1 m = 1.89 m². Windows: as measured.

What mortar mix is used in brickwork?

The most common ratio is 1:4 (cement:sand) for external walls and 1:5 for internal walls. This calculator gives you the cement and sand quantities directly.

Drywall Calculator

Last updated: 2026-05-07

Use the Drywall Calculator to get instant, accurate results. Enter your values below.

Inputs

Result

Enter values and press Calculate

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Common Sizes — Click to Fill

Wall length (m)	Wall height (m)	Sheet size	Number of layers (pcs)
4 m	2.4 m	2.88	1 pcs
6 m	2.4 m	2.88	1 pcs
8 m	2.7 m	2.88	1 pcs
10 m	2.7 m	2.88	1 pcs
12 m	3 m	3.6	2 pcs

What is the Drywall Calculator?

Drywall (plasterboard) is sold in standard sheet sizes — most commonly 1.2 m × 2.4 m — and cutting around doors, windows, and electrical boxes creates significant waste. This calculator divides your total wall and ceiling area by sheet size and adds an 8% waste factor to give you the exact sheet count to order.

You may also find the Retaining Wall Calculator, Roofing Shingle Calculator, and Insulation Batt Calculator useful.

Who Uses This Calculator?

This tool is used by homeowners adding or replacing drywall, builders framing interior walls, and renovation contractors estimating material costs.

How to Use the Drywall Calculator

Enter your Wall length.
Enter your Wall height.
Enter your Sheet size.
Enter your Number of layers.
Click Calculate to see your results instantly.

Formula

The calculator uses the following formula:

Area = Length × Height × layers; Sheets = ceil(area ÷ sheet_size × 1.08)

Worked Example

A room with 60 m² of walls and ceiling using standard 1.2 × 2.4 m sheets requires 60 ÷ 2.88 = 20.8 sheets × 1.08 waste = 23 sheets.

Step-by-Step Calculation

Wall area: 6 m × 2.7 m = 16.2 m²
Standard sheet (1.2 × 2.4 m) = 2.88 m²
Sheets with 8% waste: ceil(16.2 ÷ 2.88 × 1.08) = 7 sheets
Joint compound: ~0.5 kg/m² = 8 kg; Tape: ~1.5 m/m² = 24 m

Common Mistakes to Avoid

Calculating only the net area without adding waste for cuts around outlets
Forgetting ceiling drywall — it uses the same sheet size but needs different screws
Not accounting for double-layer firewall requirements in some rooms

Pro Tip: Hang drywall horizontally (long edge perpendicular to studs) for stronger walls with fewer butt joints. Butt joints are harder to finish than tapered edge joints — minimise them.

Frequently Asked Questions

What thickness drywall should I use?

12.5 mm (1/2 inch) is standard for most interior walls and ceilings. Use 16 mm (5/8 inch) for fire-rated assemblies and ceilings with 600 mm joist spacing. 9.5 mm is used for curved walls.

How do I calculate drywall for a ceiling?

Calculate ceiling area separately from walls. For a flat ceiling, it's simply length × width. Vaulted ceilings require calculating the slope surface area using the pitch factor (same as roofing).

Why add 8% waste factor for drywall?

Cuts around doors, windows, outlets, and switches create off-cuts that are often too small to reuse. 8% is standard for simple rectangular rooms; complex rooms with many openings may need 10–12%.

Do I need moisture-resistant drywall in bathrooms?

Yes — use green board (moisture-resistant) or cement board behind tile in wet areas. Standard drywall absorbs moisture and will deteriorate behind tiles. Cement board is required in shower and tub surrounds by most building codes.

How long does drywall compound take to dry between coats?

Each coat of joint compound needs 24 hours to dry in normal conditions (20°C, 50% humidity). Speed up drying with fans and heat, or use setting-type compound which chemically hardens in 20–45 minutes regardless of humidity.

Written and reviewed by the CalcToWork editorial team. Last updated: 2026-05-07.