Table of Contents
How Log Weight Is Estimated
Estimating the weight of a log is essential for safe transport, equipment selection, and timber sales. Log weight depends on three primary factors: the volume of the log, the density of the wood species, and the moisture content.
Freshly cut (green) logs can weigh nearly twice as much as the same log after kiln drying. This is because water makes up a significant portion of the total weight in living trees, sometimes exceeding 50% of the green weight.
Weight Calculation Formula
Wood Species Densities
| Species | Dry Density (lbs/ft³) | Green Weight Factor |
|---|---|---|
| White Pine | 28 | 1.6 - 1.8x |
| Spruce | 31 | 1.5 - 1.7x |
| Douglas Fir | 34 | 1.5 - 1.8x |
| Red Oak | 36 | 1.6 - 1.9x |
| White Oak | 40 | 1.5 - 1.8x |
| Hard Maple | 38 | 1.5 - 1.7x |
| Hickory | 42 | 1.6 - 1.8x |
| Cedar | 25 | 1.4 - 1.6x |
Moisture Content Effects
- Green / Freshly Cut (~80% MC): The heaviest state. Water can account for 40-45% of total log weight. Hardwoods are heavier green than softwoods.
- Partially Seasoned (~50% MC): After several weeks of air drying, moisture content drops. Weight decreases 15-25% from green state.
- Air Dried (~20% MC): After 6-12 months of proper air drying. Weight is approximately 60-70% of green weight.
- Kiln Dried (~12% MC): Lightest practical state. Weight is roughly 55-65% of green weight.
Frequently Asked Questions
How much does a 12-inch diameter, 8-foot oak log weigh?
A green red oak log 12 inches in diameter and 8 feet long has a volume of approximately 6.3 cubic feet. At a green density of about 65 lbs/cu ft (36 lbs dry + 80% moisture), it weighs approximately 408 lbs. After air drying to 20% MC, it drops to about 272 lbs.
Why do green logs weigh so much more than dry logs?
Living trees contain large amounts of sap water in their cells. The moisture content of freshly cut wood ranges from 30% in heartwood to over 150% in sapwood (as a percentage of oven-dry weight). This water can account for a third to nearly half of the green log's total weight.
How do I weigh a log without a scale?
Measure the small-end diameter and length, then use this calculator. For more accuracy, measure both ends and average the diameters. If the log tapers significantly, measure at the midpoint. Published log weight tables and the Doyle, Scribner, or International log rules can also provide estimates.