Marine, BWP & Waterproof · Sizes & Thickness
Marine Plywood Sizes & Thickness Guide
Marine plywood comes in the same standard sheet sizes as other grades, in four thicknesses: 6mm, 9mm, 12mm and 18mm — the right one depends entirely on what you're building.
Sheet Sizes We Stock
| Sheet Size | Metric Equivalent | Typical Use |
|---|---|---|
| 4 x 8 ft | 1220 x 2440mm | The most common size for furniture, cabinets and general carpentry |
| 5 x 10 ft | 1525 x 3050mm | Larger panels for bigger furniture runs and fewer joints |
Which Thickness Fits Your Project
6-9mm
Backing panels, drawer bottoms, and other light applications that don't carry structural load.
12mm
Shelving, partition panelling, and cabinet backs where moderate strength is enough.
18mm
The standard thickness for wardrobe and cabinet carcasses, kitchen base units, counters and most modular furniture bodies.
Thicker than 18mm?
Marine plywood is not made in 19mm or 25mm. For extra-thick, heavy-duty parts like stair treads, long shelves and door shutters, use 19mm or 25mm BWP blockboard. See blockboard thickness.
Getting an Exact Quote
Sheet pricing varies by thickness, size and current market rates for face veneer and resin — see our plywood price factors guide for what drives the cost, or contact us directly for current rates on the size and thickness you need. See our marine plywood for wardrobes guide for a specific application walkthrough.
Thickness-wise Marine/BWP rate pages: 4mm, 6mm, 9mm, 12mm and 18mm.
More Buying Guides
Frequently Asked Questions
Is 12mm marine plywood strong enough for shelving?
Yes — 12mm is a common choice for shelving and cabinet backs where moderate strength is needed without the weight and cost of a thicker sheet.
Is marine plywood available in 19mm?
No. Marine plywood comes in 6, 9, 12 and 18mm. 18mm is the standard for wardrobe, kitchen and bathroom carcasses. 19mm and 25mm are blockboard thicknesses; use BWP blockboard if you need a thicker waterproof board.
What is the thickest marine plywood?
18mm is the thickest standard marine plywood. For heavier loads such as stair treads, long shelves or door shutters, use 25mm BWP blockboard, or double up two 18mm sheets where a solid plywood edge is needed.
What are the dimensions of a standard 4x8 plywood sheet?
A 4 x 8 ft sheet measures 1220 x 2440mm and is the most commonly used size for furniture, cabinets and general carpentry work.
Does marine plywood cost more than MR plywood at the same thickness?
Yes, generally — marine grade's phenolic bonding and typically denser face veneer command a price premium over MR at any given thickness; ask us for current rates on your required size.
Need the Right Board for Your Project?
WhatsApp us your requirement and we'll recommend the right grade and thickness.