Log Weight Calculator

Log Weight Calculator by Species, Length, and Diameter

This log weight calculator estimates the weight of one or more logs from wood species, length, end diameter, moisture content, and bark allowance. Choose a cylindrical log with one diameter or a tapered log with both end diameters. The result gives volume, dry wood weight, moisture weight, bark allowance, weight per log, total weight, and equivalent US short tons or metric tonnes.

A log's weight can change widely even when its dimensions look similar. Wood species, how wet the log is, bark, knots, decay, taper, and measurement accuracy all affect the result. The tool uses an approximate species density that you can edit. It is useful for early handling, firewood, timber, and delivery planning, but a scale is the right way to confirm a load weight or sale quantity.

How Much Does a Log Weigh?

Log weight is based on log volume and wood density. A cylinder's volume is pi times its radius squared times its length. A tapered log can be estimated as a frustum using the diameters at both ends. Multiply the volume by dry wood density, adjust for moisture and bark, then multiply by the number of logs. This calculator performs those steps in metric or imperial units.

For a simple example, a cylindrical log 16 feet long and 12 inches in diameter has a volume of about 12.6 cubic feet. If its dry wood density is 40 pounds per cubic foot and its moisture content is 20%, the wood estimate is about 604 pounds before any bark allowance. A real log may differ because the diameter is not perfectly round, the trunk tapers, and moisture varies through the wood.

Measure Log Length and Diameter

Measure the log's length along its centerline from one cut end to the other. For a cylindrical estimate, measure the diameter at a representative point and use the cylindrical shape. For a tapered log, measure across both cut ends and enter the larger and smaller diameters. Take each diameter through the center of the end face rather than measuring around the bark.

If an end is oval, take two measurements at right angles and use their average as a rough diameter. If the log bends, has a large branch stub, or changes thickness sharply, a single-cylinder or simple frustum formula may not match its actual volume. Split unusually shaped wood into sections or use a scale for a better weight. Keep units consistent with the selected system.

Cylindrical and Tapered Log Methods

A cylinder assumes the log has one constant diameter from end to end. This is easy to measure and can work for a short, fairly uniform piece. A tapered log uses a larger diameter at the butt end and a smaller diameter at the top end. The calculator treats this as a circular frustum, a solid that narrows evenly between two circular faces.

Real tree trunks do not always taper in a straight line. A log may have knots, a swollen base, branches, damage, or uneven bark. The frustum model averages the cross-section along its length; it does not map each bend or change in diameter. If the log is highly irregular, use several shorter sections with their own measurements or weigh it directly when accuracy matters.

Wood Species and Density

Wood density describes how much dry wood mass fits in a given volume. Dense hardwoods such as oak are generally heavier than many softwoods such as pine or cedar, but species names cover a wide range of growing conditions. The calculator provides rough dry-density presets for pine, oak, maple, birch, and cedar. Use the custom option to enter a value from a forestry reference or local measurement.

Species presets are not guaranteed values for an individual tree. Density changes with species variety, growth rate, age, heartwood, sapwood, knots, and location. If a supplier or forestry source provides density for the exact wood and moisture basis, use it. The density field is dry wood density, and the moisture input is applied separately to estimate the added water mass.

Green, Wet, Air-Dried, and Dry Wood

Freshly cut or green wood can contain a great deal of water. As wood dries, it loses moisture and becomes lighter. Air-dried logs may still contain more moisture than kiln-dried lumber. This calculator uses moisture content as a percentage of oven-dry wood mass: 20% moisture adds about 20% of dry wood weight before the bark allowance.

Moisture varies between species, seasons, storage conditions, and even locations within one log. The surface may dry while the center remains wet. A moisture meter reading can help, but meters and procedures have limits on round wood. Use a broad estimate for planning and weigh the log if a safe lift, vehicle capacity, or sale depends on the exact mass.

Account for Bark

Bark has its own mass and moisture. The bark allowance field adds a percentage to the estimated moist wood weight. Set it to zero when the log is debarked or when your chosen density already includes bark. For bark-on logs, a small percentage is a convenient estimate, but thick bark, species, and moisture can change the amount considerably.

The percentage is not a direct measurement of bark thickness or bark volume. It is an optional weight allowance to make a rough estimate closer to a whole log. For firewood or timber sale, ask how the buyer measures the product. A scale ticket or local log rule may handle bark and volume differently from this simple weight estimate.

Log Weight for Firewood and Timber

Firewood planning often uses a mix of volume and weight. Weight affects handling and transport, while species and moisture affect how the wood burns and dries. The calculator can estimate a stack or batch if the logs are similar in length, diameter, species, and moisture. For mixed wood, calculate each group separately and add their weights.

Timber buyers may use scaling rules, board feet, cubic metres, or weight-based sale terms. This calculator estimates geometric volume and mass, but it does not apply a log scaling rule, subtract defects, or determine usable lumber yield. Confirm the method used by a mill, firewood seller, or forestry program before using an estimate for a transaction.

Plan Lifting and Transport

A log can be difficult to move because its weight is concentrated in a long, round shape that can roll. Use the estimated weight as a planning prompt, not as permission to lift or tow a load. Consider the log's center of gravity, ground slope, rolling path, equipment rating, attachment points, and safe exclusion area. Use equipment and procedures suited to the actual log.

Vehicle payload limits include passengers, fuel, equipment, and cargo, not only the wood. Multiple logs may shift while being carried, and wet ground can affect loading access. For transport or machinery limits, use a certified scale and follow the vehicle or equipment manufacturer's rating. A generic wood density should not be used to certify a load or lifting plan.

Metric and Imperial Log Measurements

Imperial mode uses feet for length, inches for diameter, and pounds per cubic foot for dry density. Metric mode uses metres, centimetres, and kilograms per cubic metre. The calculator converts your current dimensions and density when switching systems. Moisture and bark remain percentages because they do not depend on the selected units.

The weight result shows kilograms or pounds, plus both US short tons and metric tonnes. One US short ton is 2,000 pounds; one metric tonne is 1,000 kilograms. These units are close but not identical. Check which ton unit a buyer or carrier means, and confirm the scale unit before comparing a calculated estimate with a measured result.

How to Get a Better Log Weight Estimate

A careful measurement usually improves the estimate more than adding extra decimal places. Clear loose dirt and debris from the cut faces, then measure the wood itself consistently. If bark remains and you enter a bark allowance, avoid including a thick loose section in the diameter measurement as well; otherwise bark may be counted twice. Record the units beside each measurement before entering them, especially when working from a tape marked in inches and feet.

For a batch of logs, sort pieces into groups that have similar species, length, diameter, and moisture. Run a separate estimate for each group and add the totals. This takes longer than entering one average log, but it handles the difference between small top logs and larger butt logs more clearly. If only a rough group average is possible, measure several representative pieces rather than choosing the largest or smallest one.

Choose a density value that matches the moisture basis expected by the calculator. This tool starts with oven-dry wood density and adds the user-entered moisture percentage. A published density for green wood may already include water; entering that value as dry density and adding moisture again would overstate weight. Read the source notes and use the custom density field when you have reliable local data. When the source does not explain its moisture basis, treat the result as a broad planning range.

It can help to compare the estimate with a known reference. If you have a similar log that was weighed, check whether its species, dimensions, and moisture are close to the current log. One reference measurement cannot represent every tree, but it can reveal a unit mistake or a density setting that is clearly unsuitable. Keep the calculation inputs with the result so another person can understand what assumptions were used.

Using a Log Weight Estimate Responsibly

Use estimated weight to plan questions such as whether a log may need mechanical handling, whether a trailer needs closer checking, or whether several loads might be more practical. Do not treat the number as a rated load. A log's shape can make it roll, tip, or shift even when its estimated mass appears manageable. Securement, lifting points, ground conditions, equipment condition, and operator training all matter in addition to weight.

For a sale, ask the buyer how the wood is measured and what units appear on the scale ticket. A price entered per US short ton produces a simple mass-based value estimate. It does not include grading, deductions, delivery, market changes, volume scaling, or quality adjustments. It is also not a quote from a buyer. Use the agreed contract and an accepted scale or timber measurement method for financial decisions.

The volume shown is geometric volume based on the selected shape. It is not board-foot volume and does not estimate how many boards a sawmill could produce. Lumber yield depends on defects, saw kerf, dimensions, drying, and the mill's cutting plan. For firewood, the calculator does not convert to a cord because stacking gaps and local cord definitions affect the result. Use a product-specific measure when buying or selling wood by volume.

If the log is very large, hollow, forked, badly curved, or partly decayed, a simple cylinder or frustum may be a poor description. Divide it into reasonably straight sections and estimate each separately, or have it assessed with suitable weighing or forestry equipment. Do not climb, cut, or move a hazardous tree to obtain measurements. Get qualified help where falling timber, suspended loads, or chainsaw work is involved.

Log Volume and Weight Formula

For a cylinder, volume equals pi times radius squared times length. For a tapered log, volume equals pi times length divided by 12, multiplied by the sum of the large diameter squared, the product of both diameters, and the small diameter squared. The formula uses diameter values at the two ends and assumes a smooth, even taper between them.

Dry mass equals log volume multiplied by dry wood density. Moisture mass is estimated from dry mass times moisture content divided by 100. Bark allowance is applied to the wood plus moisture estimate. Per-log weight is multiplied by quantity for the total. The result converts kilograms to pounds, US short tons, and metric tonnes for easier planning.

Limits of an Online Log Weight Calculator

This calculator estimates a log as a cylinder or a smooth tapered frustum. It does not measure knots, hollow areas, branching, sweep, decay, bark thickness, or internal moisture distribution. Species presets are approximate and may not match a local variety. The diagram is a visual aid, not a forestry scale drawing or lifting plan.

Use a scale when exact weight is needed for transport, equipment limits, a purchase, or a sale. For logging volume or timber value, use the scaling method accepted by the relevant buyer or forestry service. Confirm wood density and moisture assumptions, and get qualified advice for rigging or moving heavy logs. The calculator gives an estimate, not a certified measurement.