Log Weight Calculator

Log Weight Calculator

Estimate the weight of green (freshly cut) tree logs. Calculate volume and weight based on species and dimensions.

Last updated: March 2026

Timber Weight Estimator

What is Log Weight Calculation?

Log weight calculation estimates the weight of tree logs based on their dimensions and wood species. This is essential for forestry operations, lumber industry logistics, transportation planning, and sawmill capacity management. Accurate weight estimates help determine trucking loads, crane requirements, and milling schedules.

Wood density varies significantly between species and moisture content. "Green wood" refers to freshly cut timber with high moisture content (typically 50-200% of dry weight). Oak, one of the densest hardwoods, weighs about 63 lb/ft³ when green, while cedar, a lightweight softwood, weighs only 31 lb/ft³. These densities are much higher than kiln-dried lumber.

This calculator models logs as perfect cylinders, though real logs have taper, branches, and irregular shapes. For rough timber estimates, the cylinder approximation provides sufficient accuracy. Professional foresters use more complex formulas accounting for taper and defects, but the cylindrical model is widely used for quick field estimates.

How to Calculate Log Weight

The Formula

Volume (Cylinder)
V = π × r² × L
where r = radius, L = length (in consistent units)
Weight
Weight = Volume × Density
Density varies by species (see table below)

Green Wood Densities (lb/ft³)

Oak: 63 lb/ft³
Maple: 56 lb/ft³
Birch: 50 lb/ft³
Pine: 50 lb/ft³
Ash: 48 lb/ft³
Walnut: 46 lb/ft³
Cherry: 45 lb/ft³
Spruce: 36 lb/ft³
Poplar: 34 lb/ft³
Cedar: 31 lb/ft³
* Values for green (freshly cut) wood with ~50-100% moisture content

Worked Example

Calculate weight of an oak log:

Given:
• Diameter: 12 inches
• Length: 10 feet
• Species: Oak (density = 63 lb/ft³)
Step 1:
Calculate radius in feet:
r = (diameter / 2) / 12
r = (12 / 2) / 12
r = 6 / 12
r = 0.5 feet
Step 2:
Calculate volume:
V = π × r² × L
V = 3.14159 × (0.5)² × 10
V = 3.14159 × 0.25 × 10
V = 7.85 ft³
Step 3:
Calculate weight:
Weight = V × Density
Weight = 7.85 ft³ × 63 lb/ft³
Weight = 495 lbs
Result:
495 pounds
About 0.25 tons or 225 kg

How to Measure a Log

  • Measure the average diameter across the log.
  • Measure the usable log length.
  • Use dimensions before cutting into boards.
  • Measurements including bark generally produce higher estimated weights.

Why Actual Logs Weigh Different

This calculator assumes every log is a perfect cylinder with a uniform density. Real logs taper toward the top of the tree, contain knots, irregular grain, bark of varying thickness, and moisture that changes over time. As a result, actual weights may differ by 10–30% depending on species and harvesting conditions.

Green vs. Dry Wood Weight

Freshly cut wood contains substantially more water than seasoned wood, so the same log becomes lighter as it dries. Moisture content varies by species, growing conditions, season, and storage time, which means the calculator's green-density values should be treated as estimates.

Wood ConditionTypical WeightDescription
GreenHeaviestFreshly cut wood with a high and variable moisture content.
Air-driedModerateWood that has lost moisture naturally while exposed to ambient air.
Kiln-driedLightestWood dried under controlled conditions to a lower, more uniform moisture content.

This calculator uses estimated green wood density. Do not use the result as a certified load weight for transport, lifting, or equipment limits.

Further Reading

Frequently Asked Questions

What is green wood vs dry wood?

Green wood is freshly cut and contains 50-200% moisture content (weight of water relative to oven-dry weight). Kiln-dried lumber is 6-12% moisture. Green oak weighs ~63 lb/ft³, while kiln-dried oak weighs ~47 lb/ft³. Green wood is much heavier.

Why does this overestimate weight?

The primary source of overestimation is modeling a tapered log as a perfect cylinder. Real logs are thicker at the base and taper toward the top; using mid-point diameter minimizes this but still overestimates volume. Bark and defects also contribute slightly. For precision, use Scribner or Doyle log rules that account for taper explicitly.

How accurate is the cylinder model?

Within 10-20% for rough estimates. Professional log scaling uses taper formulas and deducts for defects. For planning truck loads or crane capacity, the cylinder model provides sufficient safety margins when you round up.

Can I use this for firewood?

Yes, but firewood is typically measured in cords (128 ft³ stacked, ~85 ft³ solid wood). A cord of green oak weighs ~5,400 lbs, while dry oak is ~3,800 lbs. Moisture content dramatically affects weight.

What about board feet?

Board feet measure lumber volume (1 bf = 1ft × 1ft × 1in). To convert: board feet ≈ (diameter² × length) / 16 for Doyle rule. A 12" diameter, 10ft log yields roughly 60-70 board feet depending on milling efficiency.

Why are hardwoods heavier?

Hardwoods (oak, maple, cherry) have denser cellular structure with thicker cell walls and more material per unit volume. Softwoods (pine, cedar, spruce) have larger, less dense cells. This affects both strength and weight.

How do I measure log diameter?

Measure at the small end (top) using a diameter tape or measure circumference and divide by π. For irregular logs, average the maximum and minimum diameter. Professional foresters use the small-end diameter inside bark.

What about log transportation limits?

Semi-trucks have weight limits of 80,000 lbs gross (including truck). A typical logging truck can carry 25-30 tons of logs. Always calculate total load weight before transport to avoid overweight violations and safety issues.

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