Log Volume Calculator
Estimate gross and net cubic log volume from diameter, length, taper, bark, shape, species density, moisture, and defect deductions.
1 Real log presets
Load a field-style log setup, then adjust the end diameters, taper, bark, defect, species, moisture, and cubic method.
2 Log measurements
Calculation breakdown
3 Species density grid
4 Log and species comparison grid
The grid recalculates the same net log volume with different species densities so you can compare handling weight without changing the geometry.
5 Reference tables
| Method | Formula basis | Inputs needed | Best use |
|---|---|---|---|
| Frustum | Volume from both end radii and taper | Small diameter, large diameter, length | General tapered logs and measured sawlogs |
| Smalian | Average of small-end and large-end areas | Both end diameters and length | Fast inventory, but can read high on tapered logs |
| Huber | Midpoint area times length | Mid diameter or average end diameter | Straighter logs and short bolts |
| Small-end cylinder | Small-end area times length | Small diameter and length | Conservative quick field estimate |
| Species | Air-dry density | Typical MC range | Weight note |
|---|---|---|---|
| White oak | 47 lb/ft3 | 35% to 80% | Heavy hardwood, check loader and trailer limits |
| Douglas fir | 33 lb/ft3 | 30% to 70% | Long logs can still carry major total weight |
| Southern yellow pine | 36 lb/ft3 | 45% to 120% | Green resinous pine may be much heavier than dry stock |
| Western red cedar | 23 lb/ft3 | 25% to 60% | Light species, but volume piles up on cabin logs |
| Hard maple | 44 lb/ft3 | 35% to 70% | Dense bolts need careful stack weight planning |
| Deduction | Light value | Common value | When to raise it |
|---|---|---|---|
| Bark diameter | 0.3 to 0.8 in | 0.8 to 1.5 in | Rough oak, old pine, butt flare, thick bark |
| Shape factor | 96% to 100% | 88% to 96% | Oval stems, sweep, flare, or rough salvage logs |
| Defect factor | 3% to 8% | 8% to 20% | Rot, shake, crook, embedded wire, stain, forked logs |
| Moisture check | 12% target | 30% to 80% green | Fresh-cut pine, oak, maple, or wet yard storage |
| Sample log | End diameters | Length | Frustum volume |
|---|---|---|---|
| Small pine pole | 8 in and 10 in | 16 ft | 7.1 ft3 before bark |
| Mixed hardwood sawlog | 14 in and 17 in | 12 ft | 16.0 ft3 before bark |
| Oak butt log | 20 in and 26 in | 10 ft | 29.1 ft3 before bark |
| Softwood truck log | 24 in and 31 in | 32 ft | 132.3 ft3 before bark |
6 Practical tips
To calculate the volume of a log, several variable must be accounted for. The volume of a log take into consideration the thickness of the bark on the log, the taper of the log, and any defect in the log. The most important of these variables are the usable amount of wood in the log.
This is due to the usable amount of wood in the log ultimately determine the scheduling of the trucks that will transport these logs. To calculate the volume of the logs, you can enter the diameters of the logs, the length of the logs, the species of the logs, and the deduction for each log into this calculator to determine the volume of each log. The volume of the logs cannot simply be calculated by multiplying the length of the logs by the diameter of the logs.
How to Calculate the Volume and Weight of Logs
The diameter of logs do taper, or change from one end of the log to the other end of the log. Therefore, different method of calculating the volume of logs must be used. The frustum method calculate the volume of logs using the diameter of each end of the logs and the length of the logs.
The Smalian method calculates the volume of logs by averaging the area of the ends of the logs. However, the Smalian method can produce a high reading of the volume of logs if the logs has alot of taper. The Huber method consider the middle of the logs rather than the ends of the logs.
Each of these method can be compared to one another using this calculator. The differences between these methods are small for logs that are straight logs, but the differences are larger for logs that are a pulpwood or salvage logs since salvage logs will have more taper and flare. The thickness of the bark on logs is dependent upon the age of the tree and the species of the tree.
When logs are measure, a deduction must be made for the thickness of the bark. This will reduce the volume of logs when the inside bark diameters are measured rather than the outside logs measurement. Therefore, the same outside measurements will produce different volumes of logs for species of logs with different density of bark.
Moisture content is another variable that may be considered in calculating the weight of logs. However, moisture content will not impact the cubic volume of logs. Confusing moisture content with cubic logs will lead to incorrect calculation.
The cubic footage of logs will remain the same, but the weight of logs can be adjusted according to the moisture and the target moisture level of logs. The weight of logs calculated with water will impact the trucks’ axle load, just as the weight of logs with wood will impact the trucks’ axle load. Defects in logs are another variable that many logger underestimate.
A small percentage for shake or metal in logs will become a significant amount when applied to the total number of logs in a given load. Therefore, deductions for defect must be made in logs before they are even cut from the trees. The shape of logs can also impact the amount of wood that can be produced.
Therefore, the deduction for the shape of logs must also be made. The shape correction and defect deductions will be applied after the bark is deducted from logs. The species of logs will have different densities.
Therefore, the volume of logs will have another impact on the weight of logs produced by each species. Air-dry logs will have different weight than logs with the actual density of the logs since the actual density of the logs will feature the moisture content in the logs. The comparison grid for logs will allow individuals to see the weight of logs of the same volume but of different species.
This will be helpful in scenarios in which logs of one species are to be replace with logs of another species. The tables included on this calculator include the range for deductions for logs that are used by scalers. These logs will use the ranges for the bark of logs, the shape of logs, and the percentage of defect in logs.
These ranges are established since logs will not be the same in the woods as the logs depicted in moddern mathematical calculations. While this calculator will not replace the logger or the sawmill saw operator, it will allow for adjustment to be made in the estimation of logs for variables like the percentage of bark or the percentage of defect in the logs. This will allow sawmills and logging operation to determine how logs will change if certain variable are adjusted.
While this calculator will help logs and sawmills to calculate the volume of logs more easy, the logger will still have to make certain decision. The logger will have to determine if the diameter of the logs is measured or estimated. The logger will also have to determine if the logs should be corrected for their shape.
Additionally, the moisture content of the logs will have to be determine. However, by removing the mathematics that must be performed by sawmills or loggers to calculate volume, the logger can retain the ability to make these judgment with the logs. The main goal of this calculator will be to ensure the consistency of logs.
If the logs have the same input variable, they will produce the same amount of volume and weight. Therefore, the trucks can be loaded with logs of different variable, but if the logs have the same input variable, they will produce the same output variable. Through the use of this calculator, a load of logs can be turned into an inventory of logs that are of consistent volume and weight.
