Log Weight Calculator estimates log weight with weight = volume × density using length, end diameters, quantity, species density, and units for hauling, lifting, and site load plans.
Estimating the weight of round timber before it reaches the mill or the truck is a core task in logging and construction. A log weight calculator uses species density and log dimensions to provide a reliable mass estimate, helping crews plan lifting equipment, trucking, and on-site handling.
How a Log Weight Calculator Determines Total Load
Two approaches cover nearly every jobsite scenario: single logs measured individually, or stacked wood measured as a bulk cord or pile. For a single log, the calculator computes solid volume from the log’s geometry.
For a stack, the gross volume is reduced by a packing factor that accounts for air gaps between round pieces. Either way, the final weight is simply the solid wood volume multiplied by the density of the chosen species.
The underlying math remains straightforward, but choosing the correct volume formula and density value determines whether the estimate holds up under real conditions.
Log Volume Estimation: Tapered and Cylindrical Forms
Most logs taper— the butt end is larger than the top end. Treating them as perfect cylinders overestimates volume. The truncated cone formula corrects for that shape.
Tapered Log Formula
Volume of a single tapered log:
V = (π × L / 12) × (ds² + ds × dl + dl²)
where
Vis solid volumeLis log lengthdsis the diameter at the small enddlis the diameter at the large end
All dimensions must be in the same linear unit (feet, inches, or meters). The formula produces volume in the cubic unit of that length— cubic feet if lengths are in feet, or cubic meters if in meters.
Fully Worked Example, Imperial
Consider a red oak log 12 feet long with a small-end diameter of 10 inches and a large-end diameter of 14 inches. Convert diameters to feet:
- ds = 10 in ÷ 12 = 0.8333 ft
- dl = 14 in ÷ 12 = 1.1667 ft
Compute the squares and product:
- ds² = 0.8333² = 0.6944
- dl² = 1.1667² = 1.3611
- ds × dl = 0.8333 × 1.1667 = 0.9722
Sum those three numbers: 0.6944 + 1.3611 + 0.9722 = 3.0278
Now multiply by (π × L ÷ 12). With L = 12 ft, that multiplier is (3.1416 × 12) ÷ 12 = 3.1416.
Single-log volume = 3.1416 × 3.0278 = 9.51 cubic feet.
A load of 8 such logs gives a solid volume of 8 × 9.51 = 76.1 cubic feet.
Metric Example, Tapered
Take a log 3.6 m long, ds = 25 cm (0.25 m), dl = 35 cm (0.35 m).
- ds² = 0.0625, dl² = 0.1225, ds × dl = 0.0875
- Sum = 0.2725
- π × L ÷ 12 = 3.1416 × 3.6 ÷ 12 = 0.9425
Single volume = 0.9425 × 0.2725 = 0.257 cubic meters.
Cylindrical Approximation
When the log is nearly straight or only the mid‑section diameter is available, use the cylinder formula:
V = (π × dm² / 4) × L
where dm is the diameter measured at the midpoint. This method assumes constant cross‑section and is suitable for veneer logs or machine‑rounded poles. In practice, it can overestimate volume by 5–10% compared with the truncated cone method on naturally tapered timber.
Stack Volume and the Packing Factor
Firewood, pulpwood, and short logs are often bought and sold by the stacked cord or cubic measure. A stack’s gross volume is its rectangular envelope— width × height × length.
Because round pieces leave voids, the actual wood volume is less. The standard packing factor for random‑length roundwood stacked by hand is 0.70, meaning 70% solid wood and 30% air space.
Example: One Cord
A standard cord measures 4 ft high × 4 ft wide × 8 ft long, giving a gross volume of 128 cubic feet. Applying a 0.70 packing factor:
Solid wood volume = 128 × 0.70 = 89.6 cubic feet.
For Douglas‑fir with a dry density of about 32 lb/ft³, the stack’s total dry weight approximates 89.6 × 32 = 2,867 lb, or roughly 1.4 short tons.
Packing factor varies with log straightness, diameter, and stacking care. Tightly stacked, debarked, uniform bolts can approach 0.75–0.80. Crooked, branched, or split‑heavy piles may drop to 0.60–0.65. When no local measurement is available, 0.70 remains a defensible jobsite default.
Wood Density and Species Reference
Weight rises directly with density. Dry‑wood densities for species common in heavy timber and logging appear below. These are typical values for heartwood at 12% moisture content, consistent with the data embedded in standard lookup tables.
| Species | Dry density (lb/ft³) | Dry density (kg/m³) |
|---|---|---|
| Western red cedar | 23.1 | 370 |
| Ponderosa pine | 28.1 | 450 |
| Douglas‑fir | 31.8 | 510 |
| Southern yellow pine | 36.2–41.2 | 580–660 |
| Red oak | 43.7 | 700 |
| White oak | 46.8 | 750 |
| Hickory (shagbark) | 49.9 | 800 |
| Live oak | 61.2 | 980 |
A red oak log at 43.7 lb/ft³ weighs nearly twice as much as a western red cedar log of identical dimensions. Density is the single largest source of variation between estimates, and selecting the wrong species can throw a load plan off by hundreds of pounds.
Moisture content adds significant mass. Green wood can weigh 30–50% more than dry wood. Bark, when included, contributes an extra 10–15% by volume and weight depending on species and thickness.
Field estimates should treat the calculator’s result as a dry‑wood baseline. Apply a green‑weight multiplier if the logs are fresh, or add a safety margin when lifting and hauling.
Weight Calculation and Unit Conversions
Once the solid volume and density are known, weight follows simply:
Weight = Volume × Density
If volume is in cubic feet and density in pounds per cubic foot, weight comes out in pounds. To convert to other units commonly used in trucking and crane charts:
- Pounds to short tons: divide by 2,000
- Pounds to metric tonnes: multiply by 0.0004536 or divide by 2,204.6
- Cubic feet to cubic meters: multiply by 0.02832
- Kilograms to pounds: multiply by 2.205
Worked Weight Example
Using the 12‑ft red oak log with 9.51 ft³ of solid volume and a dry density of 43.7 lb/ft³:
Single log weight = 9.51 × 43.7 = 415.6 lb.
Eight logs: 8 × 415.6 = 3,325 lb, or 1.66 short tons. In metric, that is about 1,508 kg, or 1.51 metric tonnes.
A crane rated for 2,000 lb would be inadequate for the eight‑log lift. The estimate drives equipment selection and lifting‑lug sizing.
Practical Considerations for Jobsite Load Planning
Bark, moisture, and internal decay can all shift the final weight away from the calculated value. A log that looks sound may have hidden rot or hollow pockets, especially in older windfalls.
Weighing a representative sample on a portable scale gives the best reality check. When that isn’t possible, experienced operators add a 10–20% contingency to the calculated weight before selecting slings, chains, or a crane configuration.
Truck payload limits often constrain the number of logs per load before the bed fills up. A typical tri‑axle log truck can legally carry 80,000 lb gross vehicle weight in many jurisdictions, with the truck and trailer tare subtracting about 35,000 lb, leaving roughly 45,000 lb of payload.
If each green Douglas‑fir log weighs around 2,500 lb, the truck can haul about 18 logs per trip. Species and moisture differences can swing that number by five or more pieces— enough to trigger an overweight ticket or a second run.
On the purchase side, timber is sometimes sold by the ton rather than by board feet or cords. The calculation then runs in reverse: a buyer verifies the delivered weight against the estimated solid‑wood weight to confirm the species mix and rule out excessive moisture. Understanding the relationship between volume, density, and weight protects both buyer and seller from mis‑scaled transactions.
Accurate log weight estimates begin with careful diameter and length measurements and a species identification backed by a reputable density reference.
While field conditions rarely match textbook values, a methodical calculation anchored to the truncated‑cone or packing‑factor approach gives a number that can be trusted for planning— and then verified and adjusted as the first loads hit the scale.