Log Weight Calculator

1. Pick the species from the list.
2. Enter the small-end diameter inside the bark, in inches.
3. Optionally enter the large-end diameter for a tapered log.
4. Enter the log length in feet.
5. Read the weight in pounds and kilograms.

Here is what each result line means:

For lumber weight after milling, or the board feet in a log, see the rebar weight calculator and the concrete formwork calculator.

A log weight calculator estimates the weight of a freshly cut, green log from its diameter, length and species. Loggers, sawyers and truck drivers use it to check whether a log or a load is within lifting, trailer and bridge limits before hauling.

The tool finds the volume of the log as a cylinder, or with the Smalian formula if you supply both end diameters, and then multiplies by the green-wood density of the species.

The cylinder formula treats the log as a perfect cylinder at the small-end diameter. The Smalian formula averages the two end cross-sections and gives a better estimate when the log is noticeably tapered.

1. Convert the diameter from inches to feet by dividing by 12.
2. Find the cross-section area, or the average of two end areas for Smalian.
3. Multiply by the length for the volume in cubic feet.
4. Multiply by the green density for the weight in pounds.

Green densities range from about 27 pounds per cubic foot for western red cedar up to 63 for red oak. The heavier the species, the heavier the log by a wide margin.

Suppose you have a green Douglas fir log that is 12 inches at the small end, 16 feet long, and the green density is 38 pounds per cubic foot.

Calculation: the radius in feet is 12 divided by 24, which is 0.5. The cross-section area is pi times 0.25, about 0.785 square feet. Times 16 feet the volume is about 12.57 cubic feet. Times 38 pounds per cubic foot the weight is about 478 pounds, or roughly 217 kilograms.

If you also knew the large end was 15 inches, the Smalian formula would give a slightly higher volume and weight, closer to 550 pounds, because the log tapers outward.

Species

Dense hardwoods like oak and maple can weigh more than twice as much as light softwoods like cedar or white pine for the same size log.

Moisture Content

Freshly felled logs are green and full of water. The densities in this tool are green values. A log that has been left to air-dry for months will weigh less.

Diameter and Length

Weight goes up with the square of the diameter, so a log twice as wide is roughly four times heavier for the same length.

Bark

Bark adds 10 to 15 percent to the outside-bark diameter. Always measure inside the bark, or deduct bark thickness from the outside measurement.

Defects

Hollow or punky logs weigh less than the estimate. Check the ends for rot before relying on a calculated weight.

The table below lists the green densities used in this calculator, sourced from the USDA Forest Products Laboratory.

Green density is the weight of the wood plus all its natural water per cubic foot. Actual green moisture content varies by tree, season and stand, so the table is a planning guide, not a guarantee.

Truck and Trailer Loading

Stay within the gross vehicle weight rating and bridge limits.

Crane and Loader Sizing

Verify that the equipment can lift a log before trying.

Firewood Sales

Estimate the weight of a cord or a truckload for pricing.

Timber Cruising

Convert log scale to weight for biomass or chip estimates.

1. Measuring Outside the Bark

All log scaling uses inside-bark diameter. Bark adds 10 to 15 percent to the width, which compounds in the area calculation.

2. Using Dry Density for a Green Log

A green log holds far more water than kiln-dried lumber. Always use the green density for freshly cut logs.

3. Ignoring Taper

The cylinder formula uses only one diameter. For a log with noticeable taper, supply both end diameters for a better estimate.

4. Forgetting Hollow or Defect

A hollow or rotten log weighs less than a sound one. Check the ends.

5. No Safety Margin

Density varies tree to tree and with moisture. Add a margin when close to equipment limits.

The math is exact for a perfect cylinder or Smalian frustum, but real logs are irregular, so the result is an estimate for planning, not a weigh-scale replacement.

It depends on the species. A green Douglas fir log of that size is about 478 pounds. A red oak log the same size is about 793 pounds.

Find the volume by treating the log as a cylinder, pi times the radius squared times the length, then multiply by the green density of the species.

It averages the cross-section areas at the two ends of a tapered log and multiplies by the length. It is more accurate than a plain cylinder for logs with noticeable taper.

Inside the bark. Bark can add 10 to 15 percent to the outside diameter, which would inflate the volume and weight estimate.

Green wood is saturated with water. Drying removes most of that water, and the weight drops accordingly.

Roughly 3,500 to 5,500 pounds green, depending on the species. Dense hardwoods like oak are at the high end.

Estimate each log and add them up. Compare the total to the vehicle gross weight rating and any bridge limits on the route.

The calculator assumes a solid log. A hollow or rotten log weighs less, so reduce the estimate or weigh it instead.

Yes, but the weight is modest relative to the wood. This tool uses inside-bark diameter, so bark weight is excluded from the cylinder volume.

No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere.

• USDA Forest Products Laboratory, Wood Handbook (species green density data).
• Purdue Extension FNR-191, Log and Tree Scaling Techniques (log volume and scaling methods).
• WoodWeb, Measuring Logs and Lumber (log rule formulas and taper).