What this calculator does
Timber weight follows the same rule as any solid material: volume multiplied by density. The complication is that density varies a great deal by species and treatment, from around 570 kg/m³ for radiata pine up past 900 kg/m³ for a dense hardwood like spotted gum, so the same length of timber can weigh nearly twice as much depending on what it is cut from.
This timber weight calculator takes length, width and thickness in the sizes timber is commonly sold in Australia, along with a species preset or a fully custom density, and returns the weight of one length and of a whole order. The density is always editable, since species names and moisture content shift the real figure and a supplier's technical sheet is the better source when accuracy matters.
The formula
Convert width and thickness from millimetres to metres, multiply by length in metres to get the volume of one piece in cubic metres, then multiply by density in kilograms per cubic metre to get its weight. Multiplying by the number of lengths gives the total weight of an order.
| Term | Meaning |
|---|---|
| Density | Mass per unit volume of the timber species, in kilograms per cubic metre. Varies with species, moisture content and treatment. |
| Nominal size | The width and thickness a timber section is sold as, such as 90 mm by 35 mm framing timber. |
| Volume | Length × width × thickness of a single piece, converted to cubic metres. |
The inputs explained
| Field | What to enter |
|---|---|
| Length (m) | The length of one piece of timber, in metres. |
| Width (mm) | The width (the wider face) of the timber section, in millimetres. |
| Thickness (mm) | The thickness (the narrower face) of the timber section, in millimetres. |
| Species preset | A common Australian timber species preset. Choose Custom to type any density directly. |
| Density (overrides preset if custom, or edit directly) (kg/m³) | The density in kilograms per cubic metre. Only used when the preset above is set to Custom; otherwise the preset value is used. Overwrite it with a supplier's figure for a more accurate result. |
| Number of lengths | How many lengths of this size are being weighed, for a total order weight. |
When to use it
Estimating delivery or handling weight
Knowing the total weight of a timber order helps plan vehicle load limits, how many people are needed to carry it, or whether a delivery needs a different vehicle than a light trailer.
Comparing species for a structural or decking job
Swapping the species preset between pine, treated pine and a hardwood on the same dimensions shows how much heavier a denser species will be to lift, fix and transport, before committing to it.
Checking a supplier weight figure
Timber suppliers sometimes quote a weight per length or per pack; recalculating independently from dimensions and a known density checks that figure against the maths.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much does 90 x 35 mm timber weigh by species, at 3.6 m lengths?
The same common framing size in a range of species densities.
| Species | Total weight | Total volume |
|---|---|---|
| 570 kg/m³ | 6.46 kg | 0.0113 m³ |
| 650 kg/m³ | 7.37 kg | 0.0113 m³ |
| 750 kg/m³ | 8.51 kg | 0.0113 m³ |
| 900 kg/m³ | 10.21 kg | 0.0113 m³ |
How does total weight scale with the number of lengths?
An order of treated pine framing timber at a range of quantities.
| Number of lengths | Total weight | Weight per length |
|---|---|---|
| 1 | 8.51 kg | 8.51 kg |
| 5 | 42.53 kg | 8.51 kg |
| 10 | 85.05 kg | 8.51 kg |
| 20 | 170.10 kg | 8.51 kg |
| 50 | 425.25 kg | 8.51 kg |
Questions
Why does timber weight vary so much between species?
Wood density depends on the species' cell structure and how much of the volume is solid wood fibre versus air-filled space, plus moisture content. A dense hardwood like spotted gum packs in more mass per cubic metre than a softwood like radiata pine, which is one reason hardwoods are chosen for structural loads and softwoods for general framing.
Does moisture content affect the weight?
Yes, significantly. Green (unseasoned) timber holds much more water than kiln-dried timber and can weigh noticeably more for the same dimensions. The density presets here are approximate figures for seasoned timber; a supplier's technical data sheet will give a more precise figure for a specific product and moisture state.
Are the species presets exact?
No, they are typical approximate figures for seasoned timber, included as a starting point. Density varies within a species depending on growing conditions and moisture content, so for anything load-bearing or safety-critical, use the density figure from the timber's own specification or engineering documentation.
Can I use this for hardwood decking boards as well as framing timber?
Yes. The calculation only needs length, width, thickness and density, so it applies equally to framing timber, decking boards or any other rectangular-section timber, as long as the correct dimensions and density are entered.
For the span a timber beam can carry under load, see the timber beam span calculator. For a similar weight-from-density approach applied to stone, see the sandstone block weight calculator.