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Log Weight Calculator

Determining how much a freshly cut log weighs is essential for timber transport, equipment capacity planning, and construction logistics. This calculator uses green wood density—the weight of freshly felled timber containing its natural moisture—combined with volume calculations to estimate total weight. Simply input your wood species, log dimensions, and quantity to get precise weight figures for single pieces or stacked loads.

Last updated:

Creators Tom Wright, MSc Construction Management
5,129 people find this calculator helpful

Understanding Green Wood Density

The weight of timber depends primarily on three variables: species, volume, and moisture content. Freshly cut wood is called "green" because it retains significant water absorbed during the tree's growth. This moisture—often 50–150% of the wood's dry weight—substantially increases its density and mass compared to kiln-dried lumber.

Moisture content is expressed as the ratio of water weight to oven-dry wood weight. A freshly felled oak log might weigh 250 kg but only 100 kg after drying, reflecting the departure of water. Different species have inherently different cell structures and wood density even at identical moisture levels. Softwoods like pine are lighter; hardwoods like oak or ash are considerably heavier. Using the correct green density for your species is crucial for accurate weight estimation.

Calculating Log Volume and Weight

Log weight is determined by multiplying the green density of the wood species by the log's volume. For cylindrical logs, volume is calculated using the mid-diameter (average of the small and large end diameters) to account for taper:

dmid = (dsmall + dlarge) ÷ 2

Vlog = π × dmid² ÷ 4 × L

Weight = ρgreen × Vlog

  • d<sub>small</sub> — Diameter at the smaller end of the log, measured in your chosen units
  • d<sub>large</sub> — Diameter at the larger end of the log
  • d<sub>mid</sub> — Average diameter at the midpoint, used for volume calculation
  • L — Length of the log
  • ρ<sub>green</sub> — Green (freshly cut) density of the wood species in lb/ft³ or kg/m³
  • V<sub>log</sub> — Volume of the cylindrical log

Using the Calculator for Single Logs and Batches

The calculator handles both individual logs and lumber boards. Select your wood shape—round log or rectangular board—then choose the species from the dropdown to auto-populate green density. For round logs, enter the small and large end diameters plus length; for boards, input width, thickness, and length. The tool calculates volume automatically using the Huber formula (mid-diameter method for logs).

To find total weight for multiple pieces, specify the quantity. The calculator also supports stacking scenarios: enter the width and height of your storage area, and it will determine how many logs or boards fit within that space, then compute the combined load. This feature is invaluable for assessing transport capacity and warehouse limits.

Practical Considerations When Weighing Logs

Several real-world factors affect log weight estimates and should guide your planning:

  1. Drying reduces weight significantly — Green wood can be 50% heavier than dry wood of the same species and dimensions. If you're measuring an older, weathered log, its actual weight may be substantially less. Always clarify whether your density data applies to freshly cut or partially seasoned timber.
  2. End-to-end diameter variation matters — Logs taper from base to top. Using only one diameter measurement will skew your result. Always measure both the small and large ends—the calculator's Huber formula (using mid-diameter) gives the most accurate volume estimate for tapered timber.
  3. Transport equipment has strict limits — A standard pickup truck carries approximately 1,000 lb (450 kg). Three large oak logs can max out this capacity. Always verify your equipment's load rating before hauling; exceeding it risks damage, safety violations, and component failure.
  4. Species density varies within the same family — Oak, pine, and maple each contain multiple subspecies with different densities. English oak is denser than red oak; density can vary by 10–15%. When selecting a species from the dropdown, confirm it matches your actual timber; using the custom density option if in doubt prevents calculation errors.

Why Calculating Log Weight Matters

In forestry and construction, knowing timber weight before transport or placement prevents costly mistakes. Equipment overload can damage vehicles, injure workers, and delay projects. On-site, having volume and weight figures enables quick assessment of whether a crane, truck, or team can safely handle a load. For firewood processors and timber traders, weight calculations determine pricing and assess yield. Remote sites where scales are unavailable make this calculator indispensable—you measure the log, input the data, and get a reliable weight estimate in seconds.

Frequently Asked Questions

What does 'green weight' mean and how is it different from dry weight?

Green weight is the mass of freshly felled timber still containing its natural moisture. Green wood can weigh 50–150% more than the same timber after kiln drying because water—which is heavy and fills the wood's cellular structure—has not yet evaporated. Green density is higher, so calculations using freshly cut wood dimensions and green density values give the weight of timber as it would be immediately after felling. Dry weight assumes the wood has been seasoned, losing most moisture. For transport and load planning, always use green density if your logs are freshly cut.

How should I measure a tapered log's diameter?

Measure the diameter at the thinnest end and the thickest end using a measuring tape wrapped around the log's circumference, then convert to diameter if needed. Record both values. The calculator's Huber formula automatically averages these two diameters to estimate the mid-section diameter, which yields more accurate volume than using just one end. This averaging method accounts for the natural taper in freshly felled logs and is the industry standard for timber volume estimation.

Can I calculate the weight of stacked logs and boards?

Yes. The calculator includes stacking functions for both round logs and rectangular boards. Specify your storage area's width and height, and the tool determines how many logs or boards fit, accounting for the geometry of stacked timber (logs naturally nest with gaps at angles). It then multiplies the number of pieces by the individual piece weight to give you the total load. This is useful for assessing whether a pile fits within a truck bed or a warehouse space.

What wood species are heaviest when freshly cut?

Hardwoods like oak, ash, and hickory are among the densest; green oak typically weighs 50–60 lb/ft³. Softwoods like pine and spruce are lighter at 30–40 lb/ft³. Exotic hardwoods such as teak and ipe can exceed 50 lb/ft³ even at standard moisture levels. The calculator includes a species dropdown with pre-loaded green densities. For unusual or local timber, use the custom density option and input the species-specific green density value if available from your timber supplier or forestry data.

How does log diameter affect weight calculations?

Weight scales with the square of the diameter because volume is proportional to diameter squared (π × d²/4 × L). Doubling a log's diameter increases its volume by four times, not two. This is why small diameter variations can have outsized effects on total weight. A log with a 20 cm diameter weighs roughly four times more than an 10 cm log of the same length and species, assuming identical green density.

Why might my calculated weight differ from actual scale weight?

Several factors introduce differences: (1) moisture content variation—logs from different felling seasons or storage conditions may have different water content; (2) measurement error—even small diameter or length miscalculations compound in volume calculations; (3) internal defects—rot, hollowing, or large knots reduce density locally; (4) bark inclusion—bark adds weight and is sometimes stripped before selling. Always measure carefully, confirm the species and density value, and account for any visible damage or seasoning in your estimates.

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