Log Weight Calculator - Timber & Sawlog Mass Estimator

Calculate green and air-dried log weights, cubic volume, timber tonnage, and hauling requirements. Features custom species selection (Oak, Pine, Maple, Walnut, Cedar, Fir), dual-end diameter frustum modeling, and bark thickness factors.

Comprehensive Engineering Guide to Log Weight & Timber Mass Estimation

Accurately estimating the weight of round sawlogs, felled tree trunks, and rough-cut timber is an essential requirement across forestry operations, crane rigging, arborist services, sawmilling, and heavy freight logistics. Moving raw tree sections without knowing their mass introduces severe hazards, ranging from catastrophic crane failure and boom collapse to hazardous transport violations and broken trailer axles.

Unlike uniform building materials such as steel beams or cured concrete, green logs are living, water-bearing biological structures. A freshly felled green log can contain more water by weight than dry wood fiber. This log weight calculator combines geometric taper modeling, volumetric formulas, and empirical wood density data to determine true timber mass. If you are milling raw timber into flat boards, integrate this tool alongside our Board Foot Calculator and Lumber Calculator for seamless end-to-end timber management.

The Geometry of a Tree Trunk: Frustum vs. Cylinder Volume

Tree trunks naturally taper from the wide butt end near the stump toward the narrower crown end. While casual estimators frequently treat logs as simple cylinders, doing so using either the small-end diameter or the large-end diameter creates massive errors:

Using the small-end diameter undercalculates log volume and weight by 20% to 35%, creating dangerous crane overload hazards.
Using the large-end diameter overcalculates weight by up to 30%, causing haulers to underfill transport trailers.

The geometrically rigorous method models a sawlog as the frustum of a cone (a truncated cone). Let R be the radius at the large end, r be the radius at the small end, and L be the length of the log:

Frustum Volume (cu ft) = (π × L / 3) × [ (R / 12)^2 + ((R / 12) × (r / 12)) + (r / 12)^2 ]

Where diameters (and resulting radii) are measured in inches and length is measured in feet. Once the exact solid cubic volume is known, log weight is calculated by multiplying volume by the species-specific green density:

Total Log Weight (lbs) = Volume (cu ft) × Green Density (lb/cu ft) × (1 + Bark Factor)

Green vs. Seasoned Wood Moisture Content

The single largest variable in timber weight is moisture content (MC). In forestry and wood science, moisture content is expressed as a percentage of the wood's completely oven-dry weight:

Green Wood (Freshly Felled): Contains free water in the cell cavities and bound water within the cell walls. Moisture content frequently exceeds 60% to 100% (and in some softwoods like Western Hemlock or Cottonwood, MC can exceed 120% to 150%). Fresh oak weighs between 60 and 65 pounds per cubic foot.
Air-Dried / Seasoned Wood: After months of air drying, free water evaporates completely, leaving the wood at its fiber saturation point (~28% MC) or down to ambient equilibrium (~12% to 15% MC). Dried oak drops to 40 to 47 pounds per cubic foot.

Because arborists and crane operators almost exclusively handle freshly cut timber, calculating weight using green density values is mandatory to maintain safety buffers. If you are calculating structural load limits for dried framing members, cross-reference our Wood Beam Span Calculator.

Green & Dry Density Table for Common Timber Species

Tree Species	Botanical Classification	Green Density (lb / cu ft)	Air-Dry Density (lb / cu ft)	Avg Moisture Loss (%)
Red Oak	Quercus rubra (Hardwood)	64 lb/cu ft	44 lb/cu ft	31.3%
White Oak	Quercus alba (Hardwood)	63 lb/cu ft	47 lb/cu ft	25.4%
Black Walnut	Juglans nigra (Hardwood)	58 lb/cu ft	38 lb/cu ft	34.5%
Sugar Maple (Hard Maple)	Acer saccharum (Hardwood)	56 lb/cu ft	44 lb/cu ft	21.4%
Hickory / Pecan	Carya ovata (Hardwood)	64 lb/cu ft	51 lb/cu ft	20.3%
Southern Yellow Pine	Pinus taeda (Softwood)	55 lb/cu ft	36 lb/cu ft	34.5%
Douglas Fir	Pseudotsuga menziesii (Softwood)	40 lb/cu ft	32 lb/cu ft	20.0%
Eastern White Pine	Pinus strobus (Softwood)	36 lb/cu ft	25 lb/cu ft	30.6%
Western Red Cedar	Thuja plicata (Softwood)	28 lb/cu ft	23 lb/cu ft	17.9%
White Ash	Fraxinus americana (Hardwood)	48 lb/cu ft	41 lb/cu ft	14.6%

Hauling & DOT Highway Weight Compliance

Commercial timber haulers in North America are regulated by federal and state Department of Transportation (DOT) gross vehicle weight ratings (GVWR). A standard tractor-trailer rig has an 80,000-pound maximum highway limit without oversize permits:

Truck & Trailer Tare Weight: A typical log truck and empty grapple trailer weighs roughly 28,000 to 32,000 pounds.
Legal Payload Allowance: Leaves approximately 48,000 to 52,000 pounds (24 to 26 US tons) of allowable green log weight.
Load Planning: If hauling dense green Red Oak (64 lb/cu ft), a 25-ton payload permits only ~780 cubic feet of solid wood. In contrast, hauling dry pine permits significantly more timber volume before reaching the legal weight threshold.

Firewood Cord Measurement & Weight Factors

A standard full cord of firewood is a neatly stacked pile measuring 4 feet high, 4 feet deep, and 8 feet long, totaling 128 gross cubic feet. However, because round and split logs cannot pack together without air voids, a cord is not 128 cubic feet of solid wood.

On average, a tightly stacked cord contains 80 to 85 cubic feet of solid wood (~65%), with the remaining 35% consisting of empty air pockets between the bark. Therefore, a green cord of Red Oak weighs:

Weight = 85 solid cu ft × 64 lb/cu ft = 5,440 lbs (~2.72 US Tons)

After 12 months of proper seasoning, that same cord drops to roughly 3,740 pounds, dramatically reducing transport costs and improving burning efficiency. For site preparation and log landing pads, ground aggregate requirements can be checked with our Crushed Stone Calculator.

How to Use This Log Weight Calculator

Choose Calculation Mode: Select Single Log Weight for individual logs or crane picks, Truckload & Log Hauling for fleet transport, or Firewood Cord Weight for split timber volume.
Select Tree Species: Pick your species from the dropdown menu to load standard USDA green and air-dry density factors, or input custom values.
Enter Log Dimensions: Measure the small-end diameter, large-end diameter (in inches), and total log length (in feet). Use any exact decimal precision.
Input Bark Percentage: Leave at the standard 10% default, or adjust based on tree age and bark thickness.
Click Calculate: Instantly view the green mass, seasoned mass, true solid volume, metric tonnage, and dimensional diagrams.
Print Documentation: Click the Print button to immediately generate an isolated, single-page A4 field rigging sheet for crane and transport crews.

10 Frequently Asked Questions (Timber & Tree Mass)

1. How much does a 10-foot oak log weigh?

Weight depends directly on diameter. A green red oak log measuring 10 feet long with an average diameter of 20 inches contains approximately 21.8 cubic feet of wood. At 64 lbs/cu ft plus 10% bark, it weighs approximately 1,535 pounds (0.77 US tons).

2. Why does green wood weigh so much more than dry wood?

Living trees transport water continuously through xylem vessels and sapwood cells. When freshly cut, this sap water fills both microscopic cell cavities and cell walls, often accounting for 40% to 60% of the tree trunk's total felled mass.

3. What formula calculates the volume of a tapered log?

The frustum of a cone formula provides the most accurate geometric model: V = (π × L / 3) × (R^2 + R×r + r^2), where R and r are the large and small end radii in feet and L is length in feet.

4. How much does a full cord of green firewood weigh?

A full cord (128 gross cubic feet, containing ~80 to 85 cubic feet of solid wood) of green hardwood like oak or hickory weighs between 4,800 and 5,500 pounds (2.4 to 2.75 tons). Seasoned wood weighs between 3,300 and 3,800 pounds.

5. What is the lightest common timber species?

Western Red Cedar and Eastern White Pine are among the lightest commercial softwoods in North America, weighing only 28 to 36 pounds per cubic foot green and dropping to 23 to 25 pounds per cubic foot when dry.

6. What is the heaviest North American tree species?

Live Oak (Quercus virginiana) and Osage Orange (Maclura pomifera) are among the heaviest, with green densities exceeding 70 to 76 pounds per cubic foot and dry weights staying well above 55 pounds per cubic foot.

7. How many logs can a standard log truck haul legally?

On standard US highways with an 80,000 lb GVWR limit, legal payloads average around 24 to 25 tons (48,000 to 50,000 lbs). For average 18-inch diameter, 16-foot hardwood logs weighing ~1,900 lbs each, a truck can haul approximately 25 to 26 logs.

8. Does tree bark add significant weight to a log?

Yes. Bark typically represents 8% to 15% of a log's total gross green weight, depending on species (thick ridged pine and mature oak bark weigh significantly more than smooth birch or beech bark).

9. How do you measure log diameter accurately?

Measure across the cross-section of the log using a forestry caliper or diameter tape (D-tape). For out-of-round or oval logs, take two perpendicular measurements (narrowest and widest) and average them together.

10. How fast does a felled tree log lose weight?

Whole logs with bark intact dry very slowly through the cut end-grain, losing only 10% to 15% of their water over an entire year. Once split into firewood or sawn into dimensional boards, drying accelerates rapidly.

Log Weight Calculator (Timber & Tree Trunk Mass Estimator)