Biscuit Joint Sizes (0, 10, 20) — Dimensions & Applications (Compatible with Lamello)

June 19, 2026

Wooden biscuits, often referred to as joining biscuits or plate dowels, are oval wooden plates designed for form-fitting wood joints. The standard sizes 0, 10, and 20 define the exact dimensions for a standardised 4 mm groove width. They are fully compatible with the system developed by original inventor Lamello and serve to invisibly align and stabilise sheet materials.

What Exactly Are Wooden Biscuits?

A biscuit joint is typically made of compressed beech wood, punched diagonally to the grain. The ribbed surface ensures better glue absorption. When water-based wood glue is applied, the material swells slightly. As a result, the plate wedges itself firmly into the routed groove, creating a high-strength, durable joint between workpieces.

The cut is made with a specialised biscuit jointer, whose cutter features a standard thickness of 4 mm. The oval shape allows for a few millimetres of lateral play along the length when assembling components. This tolerance considerably eases the precise alignment of edges during assembly. They act like a precision-fit anchor inside the joint, absorbing shear forces and stabilising the structure.

Dimensions and Standards for Sizes 0, 10, and 20

The dimensions of the three most common sizes are standardised across the industry, making them universally compatible across different manufacturers. All three variants require a routing width of exactly 4 mm. The choice of size is defined by the length, width, and required routing depth in the workpiece.

Size 0: Dimensions 47 mm x 15 mm x 4 mm. The maximum routing depth per component is 8 mm. This size is primarily suitable for narrow frame joints or thin sheet materials from a material thickness of 10 mm.
Size 10: Dimensions 53 mm x 19 mm x 4 mm. The maximum routing depth is 10 mm. This is the medium size for standard cabinet joints with panel thicknesses from 13 mm.
Size 20: Dimensions 56 mm x 23 mm x 4 mm. The maximum routing depth requires 12 mm. This is the absolute standard for classic furniture making with chipboard or MDF from a thickness of 16 mm to 19 mm.

Practical Use & Selection

Selecting the appropriate biscuit size depends primarily on the material thickness of the parts being joined. A cut that is routed too deeply into a thin board will inevitably break through the outer surface. When constructing a carcass, wooden biscuits are often used simply as an alignment aid, whilst the actual tensile strength is achieved through additional fixings.

Fitters frequently secure glued boards with wood screws and furniture screws as well. For board thicknesses of 19 mm, 4mm wood screws or 3.5 mm wood screws are often used to maintain the necessary clamping pressure whilst the glue dries. If screw heads remain visible on dark furniture pieces or specific décors, joiners opt for black wood screws. Alternatively, countersunk screw heads can be concealed flush after assembly using self-adhesive wooden screw cover caps.

Related Terms

Biscuit Jointer: The guided power tool used to cut the matching 4 mm groove for the wooden plates.
Wooden Dowel: The cylindrical alternative to the flat biscuit joint. Requires more precise drilling, as it allows no lateral tolerance play during glueing.
Chipboard Screw: A frequent companion to the biscuit joint for the final mechanical fastening of carcass components.