What Is Hardboard? Tempered Hardboard and HDF Explained

Hardboard is a thin, dense sheet made of wood fibres pressed under heat and high pressure, often without added glue, usually 1/8 to 1/4 in (3 to 6 mm) thick. HDF (high-density fibreboard) is its modern, resin-bonded cousin. Both are used where a thin, stiff and cheap panel is needed: cabinet backs, drawer bottoms, pegboard and paint panels.

Types of hardboard

Type	What it is and what it is for
Standard hardboard	Untreated, one smooth face and one textured (screen) back. Backs, templates, craft work.
Tempered hardboard	Treated with oil and heat: harder, stiffer and more water-resistant. Drawer bottoms, pegboard, workbench tops, signs.
Perforated hardboard (pegboard)	Tempered hardboard with 1/4 in holes on a 1 in grid for pegboard hooks.
HDF	Resin-bonded high-density fibreboard, smooth on both faces, often white or veneered. Cabinet backs and drawer bottoms in flat-pack furniture.
Tileboard / whiteboard	Hardboard with a glossy melamine or enamel face: wet-area walls and whiteboards.

Hardboard vs HDF vs MDF

Board	Density, thickness and use
Hardboard	About 900–1000 kg/m³, 3–6 mm (1/8–1/4 in): backs, drawer bottoms, pegboard.
HDF	About 800–1000 kg/m³, 2–8 mm: backs, drawer bottoms, laminate flooring cores.
MDF	About 700–800 kg/m³, 3–30 mm: carcasses, doors, painted furniture.

Hardboard and HDF sold for furniture

Board	Thicknesses	Common sheet sizes
HDF	3 mm, 4 mm, 6 mm	2440 × 1220, 2800 × 2070
White-faced HDF (backs)	3 mm, 4 mm	2800 × 2070, 2440 × 1220
Hardboard	3.18 mm, 6.35 mm	4×8 ft, 2440 × 1220
Pegboard	3.18 mm, 6.35 mm	4×8 ft, 2×4 ft

Hardboard and HDF thicknesses

Hardboard and HDF is sold in 3 mm (1/8"), 3.18 mm (1/8"), 4 mm (3/16"), 6 mm (1/4"), 6.35 mm (1/4"). For furniture carcasses and doors, 16–19 mm is standard; thin sheets are for backs and drawer bottoms.

Hardboard and HDF sheet sizes

2440 × 1220 mm (96 1/16" × 48 1/16")
2800 × 2070 mm (110 1/4" × 81 1/2")
4×8 ft (2438 × 1219 mm)
2×4 ft (1219 × 610 mm)

Weight of a 2440 × 1220 mm sheet

At a typical density of 850–1000 kg/m³:

Thickness	Weight per sheet
3 mm	8–9 kg (18–20 lb)
3.18 mm	8–9 kg (18–20 lb)
4 mm	10–12 kg (22–26 lb)
6 mm	15–18 kg (33–40 lb)
6.35 mm	16–19 kg (35–42 lb)

Advantages

Thin, dense and stiff for its thickness
Cheap
Smooth face that paints well
A nailed-on back squares a cabinet

Drawbacks

Not structural on its own
Edges cannot hold screws
Standard hardboard swells if it gets wet
Only one smooth face on many sheets

What it is used for

Cabinet, bookcase and wardrobe backs
Drawer bottoms
Pegboard tool walls (perforated hardboard)
Underlayment, templates and jigs
Art panels and whiteboards (tileboard)
Exterior siding (special siding grades)

Tips for working with Hardboard and HDF

Use the back panel to square the cabinet: measure the diagonals before nailing.
White-faced HDF gives a clean inside without painting.
Prime hardboard with an oil-based or shellac primer before water-based paint, or the fibres raise.
Cut it with a fine-tooth blade, smooth face up on a table saw.

Frequently asked questions

What is tempered hardboard?

Hardboard soaked in oil and baked, which makes it harder, stiffer and more water-resistant than standard hardboard. Use it for drawer bottoms, pegboard and anything that takes wear.

What is the difference between hardboard and MDF?

Both are made of wood fibres, but hardboard is much denser (about 900–1000 kg/m³ against 750) and thinner, usually 3–6 mm. MDF comes thicker and is used for carcasses and doors; hardboard for backs and bottoms.

Is HDF the same as hardboard?

Nearly. HDF is bonded with resin and made in a dry process; traditional hardboard is pressed wet and held together mainly by the wood’s own lignin. In use they are interchangeable for backs and drawer bottoms.

Can you paint hardboard?

Yes. Sand lightly, prime with an oil-based or shellac primer, then paint. Tempered hardboard needs the primer most, because of its oily surface.

What thickness for a cabinet back?

1/8 in (3 mm) for small cabinets, 1/4 in (6 mm) for tall wardrobes or when you hang the cabinet through the back.

Furniture plans to build

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