How much does a sheet of plywood, MDF or chipboard weigh?

This is worth knowing before you order, because weight decides whether you can carry it, whether your car can take it, whether the shelf you are building needs stronger brackets and whether that stack of boards should be on the upstairs landing. The numbers surprise most people, particularly for MDF.

Step by step

1. Understand what drives the weight: density times volume.The area of a full sheet is fixed at about 2.98 square metres, so weight is simply thickness times density. Density is the property that varies — MDF is dense, OSB and softwood ply are much less so — and it is why boards of the same size feel so different.
2. Learn the rough figures for a full 2440 by 1220 sheet.18mm MDF around 45 to 50kg; 18mm moisture-resistant MDF slightly more; 18mm chipboard around 40kg; 18mm softwood or hardwood plywood around 30 to 35kg; 18mm birch ply around 35kg; 18mm OSB/3 around 35kg. Halve roughly for 9mm, and scale proportionally for other thicknesses.
3. Learn the plasterboard figures separately.A 2400 by 1200 sheet of 12.5mm standard plasterboard is around 22 to 25kg; 15mm around 28 to 30kg; acoustic and high-density boards considerably more, sometimes half as much again. Fire-rated and moisture-resistant boards are heavier than standard of the same thickness.
4. Work out any sheet from the density.Multiply density in kilograms per cubic metre by the thickness in metres by the area. For a full sheet that is density times thickness times 2.98. MDF is around 700 to 780, chipboard around 650, plywood 500 to 700 depending on species, OSB around 600.
5. Use the figure to decide the transport.Three sheets of 18mm MDF is around 150kg, which is more than most cars' payload once you and a passenger are in it. Weight, not just size, is a reason to have boards delivered.
6. Use it when you are calculating a load.A shelf's own weight counts against its brackets and its wall fixings. An 18mm MDF shelf a metre long and 300mm deep is around 5kg empty, and a run of them adds up.
7. Use it before you stack boards upstairs.A stack of ten sheets is around half a tonne concentrated over a small area. That is a serious point load on a domestic floor. Spread the stack across joists rather than piling it in a corner, and do not stack heavily on an upper floor at all if you can avoid it.

Tips

• Suppliers publish weight per sheet or per square metre in their technical data. If the exact figure matters — for a load, a bracket or a vehicle — get it from the manufacturer rather than a rule of thumb.
• Wet board is far heavier than dry board. A sheet that has been standing in the rain can gain several kilos, which matters both for carrying and as a warning that it is on its way to being ruined.
• Plywood is the lightest of the common structural boards for its stiffness, which is why it wins on anything that has to be lifted into position — a loft floor, a roof deck, a shed.

Common mistakes

• Assuming MDF is light because it is smooth and uniform — It is the heaviest common board per millimetre of thickness. An 18mm full sheet is genuinely difficult for one person, and this catches people out constantly at the checkout.
• Overloading a car's roof bars — Bars have a rating and roofs have a separate, often lower, rating. Two sheets of 18mm MDF exceeds many domestic roof ratings before you add the bars themselves.
• Ignoring the shelf's own weight in a load calculation — On a long span, the board can be a substantial fraction of the total load before anything goes on it, and it is applied all the time rather than occasionally.

Questions people ask