Log Weight Calculator
Enter your log dimensions and wood species to estimate total weight. The calculator uses Huber's formula for volume and USDA green-wood density figures, then adjusts for moisture content so you can compare a freshly-felled log against air-dried or kiln-dried timber. Switch between imperial (inches, feet, pounds) and metric (centimetres, metres, kilograms) at any time.
Formula
Worked example
A red oak log (green density 63 lb/ft³) with a 12-inch small end, 16-inch large end, and 8-foot length: mid-diameter = (12+16)/2 = 14 in = 1.167 ft; area = pi × 1.167² / 4 = 1.069 ft²; volume = 1.069 × 8 = 8.55 ft³; green weight = 63 × 8.55 = 539 lb. Kiln-dried (0.60 factor): 539 × 0.60 = 323 lb.
How log weight is calculated
The calculator uses Huber's formula, the standard method for estimating round-log volume. You measure the diameter at the small end and the large end; the formula averages them to get the mid-section diameter, then computes the cross-sectional area of a circle at that mid-section and multiplies by the length. That volume is then multiplied by the wood's effective density to get weight. Density depends on two things: the species (which controls how much wood fibre and natural resin is present) and moisture content (which controls how much water is carried inside the cells). Green logs fresh from the saw can be 40-80% water by weight, so a kiln-dried board of the same species and size can be nearly half the weight of its green counterpart.
Why moisture content matters so much
Freshly-felled timber is saturated with free water in the cell lumens and bound water in the cell walls. As it dries, free water leaves first (down to the "fibre saturation point" at roughly 25-30% moisture content) and weight drops quickly. Further drying removes bound water, the wood begins to shrink, and weight continues to fall but more slowly. Air-drying outdoors typically brings softwoods to 15-19% moisture content and hardwoods to similar levels over 6-18 months; kiln-drying can reduce moisture content to 6-9% in days to weeks. A green red oak log that weighs 1,000 lb might weigh only 600-650 lb once kiln-dried, a difference that matters greatly for trucking costs, crane loads and firewood caloric value.
How to measure a tapered log
Measure the diameter at the small (top) end and at the large (butt) end using a log caliper, diameter tape, or a standard tape measure across the face. For an oval cross-section, measure the short axis and the long axis and average them. Length is measured along the log's centerline. If the log is very curved or has significant sweep, Huber's formula still works well for the straight-line length, though actual volume will be slightly higher due to the sweep. For extreme cases, the Smalian or Newton formulas give a marginally more accurate volume, but Huber's is the industry default and the error is typically under 1% for typical taper.
Practical applications: trucking, rigging and firewood
Knowing log weight before transport prevents overloading a truck or trailer - most US states restrict gross vehicle weight to 80,000 lb for a standard semi. A load of 40 green red oak logs at 16 inches average diameter and 8-foot length would weigh roughly 21,000 lb, well within a standard flatbed's 48,000 lb payload. For crane or cable rigging in tree work, knowing the log's weight is essential for selecting the correct sling, rigging hardware and anchor capacity. In the firewood trade, buyers increasingly pay by weight rather than volume (cords), so green-weight versus air-dried weight affects pricing directly. This calculator's moisture-content switch lets you quote prices for all three states from a single set of log dimensions.
Green wood density by species
| Species | Green density (lb/ft³) | Green density (kg/m³) | Weight class |
|---|---|---|---|
| Spruce, Sitka | 32 | 513 | Light |
| Willow | 32 | 513 | Light |
| Fir, noble | 29 | 465 | Light |
| Cedar, western red | 28 | 449 | Light |
| Pine, white | 36 | 577 | Light |
| Poplar, yellow | 38 | 609 | Light |
| Fir, Douglas | 39 | 625 | Light |
| Pine, lodgepole | 39 | 625 | Light |
| Basswood | 42 | 673 | Medium |
| Aspen, quaking | 43 | 689 | Medium |
| Alder, red | 46 | 737 | Medium |
| Pine, ponderosa | 46 | 737 | Medium |
| Ash, green | 47 | 753 | Medium |
| Fir, white / Tamarack | 47 | 753 | Medium |
| Ash, white / Oregon | 48 | 769 | Medium |
| Hemlock, eastern | 49 | 785 | Medium |
| Cottonwood | 49 | 785 | Medium |
| Maple, red / Hemlock, western | 50 | 801 | Medium |
| Oak, red | 63 | 1009 | Heavy |
| Oak, white | 62 | 993 | Heavy |
| Oak, black | 62 | 993 | Heavy |
| Oak, pin / Hickory, shagbark / Oak, scarlet | 64 | 1025 | Heavy |
| Oak, California black | 66 | 1057 | Very heavy |
| Oak, live | 76 | 1218 | Very heavy |
Green (freshly-cut) density values from USDA Forest Products Laboratory. Kiln-dried values are roughly 35-45% lower.
Frequently asked questions
What is Huber's formula and why is it used?
Huber's formula computes log volume as the cross-sectional area at the mid-section of the log multiplied by the length. The mid-section diameter is the average of the small-end and large-end diameters. It is the most widely used single-measurement method for round logs because it is simple to apply and accurate to within 1-2% for logs with a typical taper. More complex formulas such as Smalian's (which uses the two end cross-sections) and Newton's (which requires a true mid-section measurement) are used when higher precision is needed, but Huber's is the standard for practical field estimating.
How much lighter is a dry log compared to a green one?
A fully air-dried log (around 15-19% moisture content) typically weighs 25-30% less than a green log of the same species and size. A kiln-dried log (6-9% moisture content) can weigh 35-45% less than green. The exact figure depends on species: high-density hardwoods like oak and hickory start with a very high moisture fraction in the sapwood, so the relative weight loss from drying is larger than for resinous conifers like pine.
Why does the same-size log weigh different amounts for different species?
Wood density varies enormously by species because of differences in cell-wall thickness, the ratio of heartwood to sapwood, the amount of natural resins and extractives, and the inherent density of the wood fibre itself. At the light end, balsa wood (not listed here) is under 12 lb/ft³ green, while live oak and the densest tropical hardwoods can exceed 80 lb/ft³. Among common North American species, the range from Sitka spruce (32 lb/ft³) to live oak (76 lb/ft³) means a live oak log is more than twice as heavy as the same-sized spruce log.
Can I use this calculator for firewood?
Yes. For firewood, choose "air-dried" or "kiln-dried" moisture content and enter the average dimensions of a split piece, or enter the whole-log dimensions to get the cord-load weight. Keep in mind that a standard face cord (4 ft x 8 ft x 16 in) of air-dried hardwood typically weighs 1,000-1,500 lb depending on species - that is a useful sanity check against the calculated result.
How accurate is this calculation?
Accuracy depends on how accurately you measure the diameters and length, and on how closely the actual wood matches the tabulated green density for its species. Density varies within a species by growing region, tree age and site conditions by up to plus or minus 10-15%. For planning purposes - truck loads, rigging, purchase decisions - the result is typically accurate to within 10-20% of the true weight, which is sufficient for most field applications. For precise weighing (legal loads, timber sales by weight), use a scale.
What is "green" wood?
Green wood is freshly cut timber that still contains its original moisture. The term does not refer to colour; it simply means the wood has not been dried. Green wood is significantly heavier than dried wood, cuts and works more easily with hand tools, and burns poorly in a stove because the water must be driven off before the wood can combust. The moisture content of green wood varies by species from roughly 35% to over 100% (where 100% MC means equal parts water and dry wood fibre by weight).
Can I calculate the weight of a stack of logs?
Enter the dimensions of a single representative log and set "Number of logs" to the total count in the stack. If logs vary in size, run the calculator separately for each size group and add the results. For a rough estimate of an entire cord, a face cord of green mixed hardwood typically weighs 1,800-2,500 lb, while a full cord (4 x 4 x 8 ft) can weigh 4,000-5,000 lb green and 2,500-3,500 lb air-dried.