Enter any two of the three fields (log radius, log length, or green log weight) into the Green Log Weight Calculator, and enter an estimated green wood density. The calculator will evaluate the estimated Green Log Weight.
Understanding the Green Log Weight Calculator
The green log weight calculator estimates the weight of a freshly cut or not fully dried log from its size and an assumed green wood density. This is useful when planning lifting, hauling, milling, storage, or equipment capacity. Because the calculation models the log as a cylinder, the result should be treated as an estimate rather than an exact scale weight.
Green Log Weight Formula
GLW = \pi r^2 L \rho
Where:
- GLW = green log weight
- r = log radius
- L = log length
- ρ = green wood density
Use consistent units. For example, if radius and length are entered in feet and density is in lb/ft³, the resulting weight will be in pounds. If metric units are used, keep dimensions in meters and density in kg/m³ to get weight in kilograms.
If You Need to Solve for a Different Variable
The calculator can also solve for the missing dimension when the other values are known.
L = \frac{GLW}{\pi r^2 \rho}r = \sqrt{\frac{GLW}{\pi L \rho}}Using Diameter Instead of Radius
Many logs are measured by diameter, but this calculator uses radius. Convert diameter to radius first:
r = \frac{D}{2}You can also write the weight formula directly in terms of diameter:
GLW = \pi \left(\frac{D}{2}\right)^2 L \rho = \frac{\pi D^2 L \rho}{4}Input Guide
| Input | What it means | Why accuracy matters |
|---|---|---|
| Log radius | Half of the log diameter | Weight changes with the square of radius, so a small diameter error can create a large weight error. |
| Log length | The measured usable length of the log | Weight increases directly with length. |
| Green wood density | An estimate of the wood’s weight per unit volume while green | Density scales the result directly; higher density means a heavier log. |
| Green log weight | The estimated total weight of the log | This is the output used for handling, transport, and planning. |
Example Calculation
Suppose a log has a radius of 0.75 ft, a length of 10 ft, and an estimated green density of 60 lb/ft³.
V = \pi (0.75)^2 (10) \approx 17.67 \text{ ft}^3GLW = 17.67(60) \approx 1060.3 \text{ lb}That log would weigh about 1,060 lb, or roughly 0.53 short tons.
Why Actual Log Weight May Differ
Real logs are rarely perfect cylinders. Actual field weight may be higher or lower than the estimate because of:
- Taper: a butt-end measurement carried across the full length can overstate volume.
- Bark: thick bark adds weight and changes the effective diameter.
- Species differences: green density varies significantly from one wood type to another.
- Moisture variation: partially dried logs weigh less than freshly cut logs.
- Irregular shape: out-of-round sections, crook, flare, or knots affect volume.
- Defects: hollows, decay, and voids reduce actual weight.
- Surface material: mud, water, ice, or snow can add handling weight.
Tips for Better Estimates
- Measure diameter carefully and convert it to radius before entering the value.
- Use an average diameter if the log is noticeably out of round.
- For tapered logs, estimate the weight in shorter sections and add the results.
- Match the density value as closely as possible to the species and moisture condition.
- If the number is being used for transport or lifting, leave an appropriate safety margin.
Common Unit Conversions
| Conversion | Value |
|---|---|
| 1 ft | 12 in |
| 1 m | 100 cm |
| 1 short ton | 2,000 lb |
| 1 metric ton | 1,000 kg |
| 1 lb | 0.453592 kg |
Frequently Asked Questions
What does “green” mean?
“Green” refers to wood that still contains substantial natural moisture and has not been fully seasoned or dried.
Is green log weight the same as dry log weight?
No. Green logs normally weigh more because they contain more moisture. As wood dries, its density and total weight decrease.
Should I measure diameter with or without bark?
Either approach can work, but your density assumption should match your measurement method. If diameter includes bark, the estimate will generally be heavier than a wood-only measurement.
Why does radius matter so much?
Because cross-sectional area depends on the square of radius, even a modest change in radius can produce a much larger change in estimated weight.
When is this calculator most useful?
It is especially helpful for quick field estimates, sawmill planning, log handling, trailer loading, and checking whether equipment capacity is in the right range before moving a log.
