What is the standard plywood sheet size in the UK?

The standard plywood sheet size in the UK is 2440 × 1220mm (8 × 4 feet), giving an area of approximately 2.977m² per sheet. Handy panels at 2440 × 610mm (8 × 2 feet) are also widely available and easier to transport in a car. Both sizes are stocked by all major UK timber merchants.

What thickness plywood do I need?

The thickness depends on the application: 9mm for wall sheathing and non-structural lining, 12mm for general cladding and light shelving, 18mm for flooring, worktops and structural applications (the most popular all-round thickness), 22mm for heavy-duty flooring and subfloors, and 25mm for structural flooring and countertops. For structural use, check the plywood is rated to BS EN 636.

What is the difference between plywood and OSB?

Plywood is made from thin veneers of real wood glued in alternating grain directions, giving it excellent strength in all directions. OSB (Oriented Strand Board) is made from compressed wood strands bonded with resin. Plywood is stronger, smoother and more water-resistant, but more expensive. OSB is cheaper and widely used for sheathing, flooring underlayment and structural bracing where appearance doesn't matter.

How much wastage should I allow for plywood?

Allow 10% wastage for rectangular areas with few cuts. Increase to 15% for rooms with alcoves, bay windows or complex shapes. For angled cuts (e.g., fitting around roof trusses), allow 15-20%. When sheeting a whole floor, offcuts from one row can often start the next row, reducing waste.

Can I use plywood instead of floorboards?

Yes. 18mm or 22mm structural plywood (BS EN 636-2 or -3) is commonly used as a subfloor over joists. It provides a flat, stable surface for laminate, vinyl or tile. For tongue-and-groove jointed sheets, use 22mm P5 chipboard or T&G plywood. Ensure joists are at 400mm centres for 18mm or 600mm centres for 22mm boards.

How do I cut plywood without splintering?

Use a fine-toothed blade (60+ teeth for circular saw, 10+ TPI for jigsaw). Cut with the good face up when using a table saw, or good face down with a circular saw or jigsaw (the blade cuts upward, so splintering occurs on the top face). Apply masking tape along the cut line to reduce tear-out, and support the sheet near the cut to prevent it sagging.

Plywood & OSB Sheet Calculator — How Many Sheets Do I Need?

How We Calculate This

This calculator determines how many plywood or OSB sheets you need to cover a given area, factoring in sheet dimensions, cutting layout and optional wastage.

Sheet sizes

Standard sheet: 2440 × 1220mm = 2.977m²
Handy panel: 2440 × 610mm = 1.488m²

Calculation method

The calculator uses two methods and takes the higher result:

Area method: Sheets = ceil(Total Area / Sheet Area)
Layout method: Sheets per row × rows, checking both sheet orientations and picking the one that uses fewer sheets

Cutting optimisation

The layout method considers how sheets physically fit across the width and along the length. It checks both orientations (sheets landscape vs portrait) and selects the more efficient layout. The offcut area shows how much material you'll have left over for other projects.

Wastage

A default 10% wastage is added to cover saw cuts (kerf), damaged edges, measuring errors and pieces that can't be reused. Adjust this upward for complex layouts.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Verify with your supplier.