A cubic metre of wood — in Danish simply called a kubikmeter or colloquially a kuub — is the universally used volume unit in the timber trade. Whether you are ordering planks for a terrace, specifying structural beams for a construction project, or just trying to understand a supplier's quote, knowing what one cubic metre actually represents saves you from expensive miscalculations.
This guide explains the concept from the ground up: how volume is calculated, why the same cube can weigh anywhere from 350 kg to over 900 kg depending on species, and how to apply these figures in real-world buying decisions. If you are specifically interested in the species used for outdoor furniture, the deep-dives on teak wood and fir wood make a useful next step.
Hardwood species such as acacia and meranti — the kind you find in quality garden furniture — sit at the denser end of the scale. Curious how those densities translate into real products built to last?
A cubic metre is simply a volume equal to 1 metre × 1 metre × 1 metre. That is the definition — nothing more complicated than three dimensions multiplied together. The formula works for any shape of timber:
| Dimension | Example value | Role in calculation |
|---|---|---|
| Length | 2.00 m | The longest axis of a plank or beam |
| Width | 0.20 m | Across the face of the plank |
| Thickness | 0.05 m | The thinnest dimension |
| Volume | 0.020 m³ | 2.00 × 0.20 × 0.05 |
That single plank occupies 0.020 m³. Stack 50 identical planks and you have exactly 1 m³ of timber. This is the arithmetic timber merchants use when pricing bulk orders, and the same logic applies whether you are specifying pine, Douglas fir, or tropical hardwood for outdoor use.
One subtlety worth knowing: a stere (often used for firewood) is a stack measuring 1 m × 1 m × 1 m, but because air gaps exist between the logs the actual solid wood content is roughly 0.6–0.7 m³. When timber suppliers quote cubic metres for sawn timber, they always mean solid volume — no air included.
Volume is fixed, but weight is not. The mass of one cubic metre depends entirely on the density of the species and its moisture content. Freshly felled (green) timber can be 30–50 % heavier than the same wood kiln-dried to 12 % moisture. This matters for transport costs, structural load calculations, and the feel of finished furniture.
| Species | Category | Approx. density (kg/m³) |
|---|---|---|
| Spruce (Picea abies) | Softwood | ~450 |
| Scots pine (Pinus sylvestris) | Softwood | ~500 |
| Fir / Douglas fir | Softwood | ~530 |
| Oak (Quercus spp.) | Hardwood | 700–800 |
| Mahogany (Swietenia spp.) | Hardwood | ~650 |
| Meranti | Hardwood | ~640–710 |
| Acacia | Hardwood | ~750–850 |
| Teak | Hardwood | ~650–750 |
All figures above are for air-dried or kiln-dried timber at approximately 12 % moisture content.
A higher density generally signals tighter grain, greater hardness, and better natural durability outdoors. That is why garden furniture crafted from acacia or meranti does not need to be as bulky as softwood equivalents to achieve the same structural strength — and why a well-made hardwood bench can outlast several generations of treated pine. Read more about the specific characteristics of teak if you are weighing up tropical hardwood options.
The density and durability figures above are not abstract — they explain why the following pieces are built the way they are. Acacia and meranti are chosen specifically because their tight, heavy grain resists weathering without requiring constant maintenance.
Here is the method used in the timber trade — straightforward once you are comfortable with it.
| Plank size (L × W × T) | Volume each (m³) | Pieces per 1 m³ |
|---|---|---|
| 2.0 m × 0.10 m × 0.025 m | 0.0050 | 200 |
| 2.0 m × 0.14 m × 0.028 m | 0.00784 | ~128 |
| 2.0 m × 0.20 m × 0.050 m | 0.020 | 50 |
| 3.0 m × 0.15 m × 0.050 m | 0.0225 | ~44 |
Once you know the volume of a single piece, scaling up to a full order is simple multiplication. Suppliers quoting by the cubic metre are using exactly this method on their end.
The hardwood roll border above is a good example of a product where knowing the exact dimensions lets you calculate how many panels cover a given length of garden bed — and how much solid hardwood you are actually buying.
In building projects, all structural timber — joists, beams, rafters — is specified and ordered in cubic metres. A cubic metre of construction-grade spruce at ~450 kg/m³ is significantly lighter to handle and install than the same volume of dense hardwood, which influences the choice of species beyond just cost. For a deeper look at species used in construction contexts, see our guide on Douglas fir.
Wholesale timber is universally traded by the cubic metre. When a merchant quotes you a rate, that rate covers one solid cubic metre of sawn, graded timber. Understanding the calculation means you can verify quotes, compare suppliers, and avoid ordering more — or less — than you actually need.
Furniture makers and buyers rarely order a full cubic metre at once, but the same volume-based thinking applies. Knowing that acacia runs at ~750–850 kg/m³ explains why a solid hardwood lounger is noticeably heavier than an equivalent piece in pine — and why it stays put on a windy terrace without ballast. If you are budgeting for a broader woodworking setup, our page on the cost of a basic woodworking setup is a useful companion read.
It depends entirely on the species and moisture content. Softwoods such as spruce or pine typically weigh 450–500 kg per cubic metre when dry. Dense hardwoods like oak or acacia range from 700 to 850 kg/m³. Freshly felled (green) timber of any species can be 30–50 % heavier than the same wood after drying.
Multiply length × width × thickness, all measured in metres. A plank that is 2.0 m long, 0.14 m wide and 0.028 m thick has a volume of 2.0 × 0.14 × 0.028 = 0.00784 m³. Add together the volumes of all individual pieces to get your total order volume.
Not quite. A stere is a stack measuring 1 m × 1 m × 1 m, but the air gaps between logs mean the actual solid wood content is only around 0.60–0.70 m³. For sawn or planed timber, suppliers always quote solid cubic metres with no air allowance.
The terms "hardwood" and "softwood" refer to botanical origin (deciduous versus coniferous trees), not strictly to hardness. Deciduous hardwoods grow more slowly and develop a denser, more complex cellular structure with smaller pores. This tighter grain accounts for their higher density, greater surface hardness, and generally better natural durability when used outdoors. Species like teak add natural oils to the equation, further improving weather resistance.
Calculate the volume of a single plank (length × width × thickness in metres) and divide 1 by that figure. A standard 2.0 m × 0.14 m × 0.028 m decking plank has a volume of 0.00784 m³, so approximately 128 planks make up 1 m³. Use our quick-reference table above for common sizes.
Moisture content affects weight significantly, but not the volume calculation itself. One cubic metre of green oak and one cubic metre of kiln-dried oak occupy the same space — the kiln-dried piece simply weighs considerably less. For structural calculations or transport planning, always check whether a density figure refers to green or dry timber.
Whether you are specifying structural timber, planning a decking project, or simply trying to understand a supplier invoice, these fundamentals give you the confidence to read any timber quote correctly. For more background on specific species, explore our guides on pine wood, fir wood, and teak wood.
The hardwoods with the highest densities — acacia, meranti, teak — are exactly the species used in outdoor furniture that is made to last. Browse the range below.
