What is the standard plasterboard size in the UK?

The most common UK plasterboard size is 2400 × 1200mm (8ft × 4ft), covering 2.88 m² per sheet. Other standard sizes include 1800 × 900mm (6ft × 3ft, 1.62 m²), 1200 × 900mm (4ft × 3ft, 1.08 m²), and 2400 × 600mm (8ft × 2ft, 1.44 m²). Standard thicknesses are 12.5mm for walls and 12.5mm or 15mm for ceilings.

How much waste should I allow for plasterboard?

Add 10% waste for simple rectangular rooms with few openings. Use 12 to 15% for rooms with many corners, alcoves, sloped ceilings, or irregular shapes. Professional plasterers typically use 10 to 12%. Waste comes from cuts around doors, windows, electrical boxes, and sheets that get damaged during handling or transport.

How many plasterboards do I need for a 12×12 room?

For a standard 3.7m × 3.7m room (roughly 12ft × 12ft) with 2.4m walls, 1 door, and 2 windows: wall area = 2 × (3.7 + 3.7) × 2.4 = 35.52 m², subtract 4.39 m² for openings = 31.13 m² net. With 10% waste = 34.24 m². Using 2400×1200mm boards (2.88 m² each), you need 12 boards for walls. Add 5 boards for the ceiling = 17 boards total.

How many screws do I need per plasterboard sheet?

Use approximately 32 to 36 drywall screws per 2400×1200mm sheet, or about 10 screws per m². On stud walls at 400mm centres, space screws every 150 to 200mm along edges and every 200 to 300mm in the field. For ceilings, use closer spacing, every 150mm along edges. A standard box of 1,000 screws covers about 30 sheets.

What's the difference between plasterboard and drywall?

Plasterboard and drywall are the same product: gypsum panels sandwiched between paper liners. 'Plasterboard' is the UK, Australian, and Commonwealth term, while 'drywall' is the US and Canadian term. Other names include wallboard, gypsum board, and Sheetrock (a brand name). The product is identical in construction.

How do I calculate plasterboard for ceilings?

For ceilings, multiply room length by width to get the ceiling area (e.g., 3.7m × 3.7m = 13.69 m²). Add 10% waste = 15.06 m². Divide by board area (2.88 m² for 2400×1200mm) and round up: 15.06 ÷ 2.88 = 5.23, so 6 sheets. For rooms wider than 1200mm, lay boards perpendicular to joists and stagger the joints.

What thickness plasterboard should I use for walls?

Use 12.5mm plasterboard for standard walls and ceilings. This is the most common thickness in UK construction. Use 15mm for ceilings requiring better sag resistance or fire rating. Use 9.5mm for overlaying existing walls or curved surfaces. For stud walls, 12.5mm on each side with insulation between is standard for internal partition walls.

How many bags of joint compound do I need per plasterboard sheet?

Plan for about 0.39 kg of joint compound per m² of plasterboard for a standard 3 coat finish (tape coat + 2 finish coats). A 12.5kg bag covers approximately 32 m². For a typical 3.7m × 3.7m room (walls only, about 31 m² net), you'll need about 1 bag of joint compound. For walls and ceiling (about 45 m²), buy 2 bags.

Plasterboard Calculator

Room Dimensions

Room Length (m)

Room Width (m)

Wall Height (m)

Include Ceiling

Openings

−4.8 m²

Door 1

Width (m)

Height (m)

Window 2

Width (m)

Height (m)

Board Settings

Board Size

Thickness

Waste Factor

Show Materials Estimate

Cost estimate

2400 × 1200mm (2.88 m²)

30.75 m² net area · 10% waste included

Plasterboards needed

12sheets (11 base + 1 waste)

2.88 m² per sheet3.7 × 3.7 × 2.4 m

Project Summary

Area breakdown, board coverage, and weight

Net wall area

30.75 m²

35.52 m² walls

Openings deducted

4.77 m²

2 openings · 35.52 m² gross

Area with waste

33.83 m²

10% waste factor applied

Total weight (est.)

294 kg

12.5mm plasterboard · ~24.5 kg per sheet

Materials Estimate

Joint compound, tape, and screws for 12 sheets

Joint compound

1 bags

11.99 kg needed · 12.5 kg bags (UK standard)

Joint tape

1 rolls

27.68 m needed · 90 m rolls (UK standard)

Drywall screws

308 screws

1 box of 1,000 · ~10 screws per m²

Calculation Breakdown

Step-by-step from room dimensions to sheet count

Step	Calculation	Result
1	2 × (3.7 + 3.7) × 2.4	35.52 m² walls
2	1× door (0.9×2.1m), 2× window (1.2×1.2m)	−4.77 m²
3	Net area × (1 + 10%)	30.75 → 33.83 m²
4	33.83 ÷ 2.88 m² per sheet	12 sheets
Plasterboards to Order		12sheets

What Is a Plasterboard Calculator?

Estimate boards, materials, and cost for walls and ceilings using UK standard sizes.

A plasterboard calculator estimates how many sheets of plasterboard you need for walls and ceilings, plus finishing materials like joint compound, tape, and screws. It prevents over-ordering (wasted money) and under-ordering (delayed projects and dye-lot mismatches).

Plasterboard (also called drywall, wallboard, or gypsum board) is the most common interior wall and ceiling lining in UK homes. In the US? Try our Drywall Calculator for imperial units and US sheet sizes.

2.88

m² per sheet

Standard 2400×1200mm

10%

waste factor

Recommended minimum

24 kg

per sheet

Standard 12.5mm board

Plasterboard Calculation Formulas

Core formulas used for area and sheet estimation in metric units.

Step 1.Wall area

2 × (Length + Width) × Wall Height

Step 2.Add ceiling (optional)

Wall Area + (Length × Width)

Step 3.Subtract openings

Total Area − (Doors × width × height) − (Windows × width × height)

Step 4.Sheets needed

⌈Net Area × (1 + Waste%) ÷ Sheet Area⌉

⌈⌉ means round up. Always buy whole sheets. Deductions use your actual opening dimensions. Defaults: 1.89 m² per door (0.9×2.1m), 1.44 m² per window (1.2×1.2m).

UK Plasterboard Sizes & Thickness Guide

Standard sheet dimensions and when to use each thickness.

2400 × 1200mm

Most common, standard walls and ceilings

2.88 m²

24.5 kg (12.5mm)

1800 × 900mm

Smaller rooms, easier solo handling

1.62 m²

13.8 kg (12.5mm)

1200 × 900mm

Patch repairs, small areas

1.08 m²

9.2 kg (12.5mm)

2400 × 600mm

Narrow walls, soffits, cladding

1.44 m²

12.2 kg (12.5mm)

Thickness Guide

9.5mm

Overlaying existing walls, curved surfaces

6.8 kg/m²

12.5mm

Standard walls and ceilings (most common)

8.5 kg/m²

15mm

Fire-rated walls, garage ceilings, soundproofing

10.5 kg/m²

Common Plasterboard Estimation Mistakes

Avoid these pitfalls to prevent costly over-ordering or project delays.

Forgetting the waste factor. Cuts around outlets, corners, and windows generate 10 to 15% scrap.

Using floor area instead of wall area. You are covering walls (perimeter × height), not the floor.

Ignoring ceiling coverage. Ceilings add 30 to 50% more plasterboard to a room.

Skipping door and window deductions. A standard UK room has 4 to 6 m² of openings to subtract.

Choosing the wrong sheet size. 2400×1200mm is standard, but 1800×900mm is easier to handle solo.

Forgetting finishing materials. Joint compound, tape, and screws add £2 to £4 per m² of plasterboard.

Pro Tips for Buying Plasterboard

Expert advice for accurate ordering, storage, and installation.

Buy 1 to 2 extra sheets beyond your calculation. Damaged sheets during transport or installation are common.

Standard plasterboard has tapered edges on the long sides. Keep factory edges together for easier jointing.

For bathrooms and kitchens, use moisture resistant (green) plasterboard to prevent mould and warping.

For garages and between-floor ceilings, building regulations require fire resistant (pink) 15mm board.

Order all sheets at once from the same batch. Slight colour differences between batches show through paint.

Store plasterboard flat on a dry surface, never standing on edge. It warps and cracks easily. Stack on timber battens.

Frequently Asked Questions

Common questions about plasterboard estimation, materials, and costs

Multiply the room perimeter (2 × (length + width)) by the wall height to get wall area. Add ceiling area (length × width) if boarding the ceiling. Subtract door and window areas. Add 10% waste. Divide by the area of one plasterboard sheet (e.g., 2.88 m² for 2400×1200mm) and round up. For example, a 3.7m × 3.7m room with 2.4m walls needs about 12 sheets of 2400×1200mm plasterboard for the walls.

Standard 12.5mm 2400×1200mm plasterboard costs £8 to £12 per sheet at UK builders' merchants (Wickes, B&Q, Travis Perkins). Moisture resistant (green) board costs £12 to £16. Fire resistant (pink) board costs £14 to £20. Sound resistant board costs £18 to £25. Bulk orders of 25+ sheets often qualify for trade discounts of 5 to 10%. Prices vary by region, retailer, and market conditions. Check your local merchant for current rates.

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Last updated May 3, 2026