Weight is volume times the wood's green density
Treat the log as a cylinder to get its volume, then multiply by the density of that species while it is still wet. The species sets the base density; the moisture in the wood is what makes a fresh log heavy. A 30 cm × 4 m pine log runs about 210 kg green and closer to 140 kg once air-dried.
Green density by species
| Species | Green density | lb/ft³ | Notes |
|---|---|---|---|
| Cedar | 450–500 kg/m³ | 28–31 | Very light |
| Spruce | 650–700 kg/m³ | 40–44 | Light softwood |
| Pine | 700–750 kg/m³ | 44–47 | Common softwood |
| Larch / Birch | 750–800 kg/m³ | 47–50 | Dense, durable |
| Maple | 800–850 kg/m³ | 50–53 | Hard, heavy |
| Oak | 800–900 kg/m³ | 50–56 | Heaviest common log |
Figures are for green (freshly cut, ~100% moisture) wood. Oak and maple weigh nearly twice as much as cedar for the same size log, so species matters as much as dimensions when you plan lifting or transport.
Moisture content changes the answer most
The same log can weigh very differently depending on how long it has dried. Moisture content is measured against the dry weight, so 100% means the water weighs as much as the wood.
A 30 cm × 4 m pine log loses roughly a third of its weight going from freshly cut to air-dried — the difference is water evaporating over months.
- Green. Freshly cut, 100% moisture or more. This is the heaviest state and what you lift in the field.
- Air-dried. Left to season for months, settling at roughly 15 to 30% moisture outdoors.
- Kiln-dried. Force-dried to 6 to 15%, the driest state and used for finished lumber.
Common questions
Why is freshly cut wood so much heavier than dry wood?
A green log is full of water. At 100% moisture content the wood holds about as much water by weight as the wood fibre itself, so a fresh log can weigh 40 to 50% more than the same log air-dried. That water is the single biggest reason weight estimates go wrong.
How do I measure the diameter of a log that is not round?
Measure it in two directions at right angles and average the two figures. For a rough estimate, take readings at the top, middle and butt and average those. The volume depends on the square of the radius, so a small diameter error moves the weight a lot.
Does the bark count toward the weight?
Yes. Bark adds roughly 8 to 15% of the weight of a fresh log, depending on species and thickness. If your log still has its bark on, expect the real weight to sit above a bare-wood estimate.
