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Log Weight Calculator

Estimate log weight from diameter, length, and a user-entered wood weight per cubic foot, with clear limits for taper and moisture.

Varies by species and moisture content. No default is assumed.

Result

636.2 lb

A 1.5ft diameter, 8ft long log weighs about 636.2 lb

Quick Answer

A log weight calculator treats the log as a uniform cylinder. Volume is pi times radius squared times length, and weight is volume times the entered wood density. A 1.5 foot diameter, 8 foot log has 14.137 cubic feet. At 45 lb/cu ft, the result is 636.2 lb.

Log Weight Explained From Diameter, Length And Density

This tool estimates log weight by treating the log as a uniform cylinder. Divide the log width by two to get radius, then use pi times radius squared times length to find cubic feet. The calculator multiplies volume by the entered wood density in lb/cu ft, which should match both species and moisture condition because green and dry wood can have very different weights. Measure diameter at several points when the log tapers, since one large end can overstate the full shape and produce a poor load estimate. The result helps with early load plans, but bark, knots, rot, hollow spots, a wide butt, and rough shape can change the true weight during lifting or transport.

How Cylinder Volume And Wood Density Set Log Weight

Log weight starts with cylinder volume. Radius comes from half the measured diameter, round-end area is pi times radius squared, and length turns that area into cubic feet. Multiplying by the entered lb/cu ft value gives the estimated weight.

  • Radius = diameter ÷ 2.
  • Round-end area = π × radius².
  • Log volume = round-end area × length.
  • Log weight = volume × lb/cu ft.

Log Weight Calculator Steps For Size And Wood Density

Inputs

  • Diameter: a representative width across the log in feet.
  • Length: end-to-end log length in feet.
  • Species density: wood weight in lb/cu ft at a known moisture level.

Steps

  1. Measure the log length.
  2. Measure width at a few points.
  3. Choose a representative diameter.
  4. Find the right lb/cu ft value.
  5. Enter all three values.
  6. Read volume and weight.

Log Weight Example With Cylinder Volume And Pounds

1.5 ft diameter, 8 ft length, and 45 lb/cu ft.

  1. Radius: 1.5 ÷ 2 = 0.75 ft.
  2. Round-end area: π × 0.75² = 1.767146 sq ft.
  3. Log volume: 1.767146 × 8 = 14.137167 cu ft.
  4. Log weight: 14.137167 × 45 = 636.1725 lb.

The estimate is 636.2 pounds, rounded to one decimal place. The steps keep more digits until the final result.

When A Log Weight Estimate Supports Handling Plans

Use the result for a preliminary load assessment or a discussion with a hauler. For a heavy or irregular log, use a scale, a safety margin, and a trained lift crew.

Measure diameter at more than one point when the log tapers. The average of the small-end and large-end diameters gives a better input than the large end alone. For related wood quantity work, compare the firewood calculator, browse construction calculators, or check terms in the glossary.

Assumptions

  • The log is treated as one solid uniform cylinder.
  • Diameter stands for the full log length.
  • The lb/cu ft value matches wood type and moisture.
  • Bark sits inside the measured width.
  • Inputs use feet and lb/cu ft.

Limitations

  • This calculator approximates a log as a uniform cylinder; taper, bark, and moisture content will change the actual weight.
  • Taper and a wide butt can raise or lower volume.
  • Rot and hollow spots can lower weight.
  • Sap and high water content can raise weight.
  • The result does not rate lift or haul gear.

In Practice

The main uncertainty often comes from wood density, not from pi. Note the species and moisture condition before selecting that value. For a strong taper, use two or more short cylinder sections instead of one full-length cylinder.

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Frequently Asked Questions About Estimated Log Weight

Where Can I Find Wood Density By Species?

Use a wood, forest, or supplier table that names both species and moisture state. USDA wood data shows that these values change by species and water content. Do not copy a value without its basis.

Why Does Moisture Content Change Log Weight?

Moisture content changes log weight because water adds mass within the wood structure. A fresh log can weigh far more than a dry log from the same tree type. Use a lb/cu ft value that fits the current state of the log.

Should Diameter Be Measured With Or Without Bark?

Diameter should use the same measurement basis as the weight calculation being made. Outside-bark width gives the full log that must be moved. A forest volume taken inside bark is a different measure and should not be mixed with outside-bark size.

How Can I Estimate A Strongly Tapered Log?

Split the log into short parts and treat each part as a cylinder. Find the weight of each part, then add the results. This reduces estimation error from one width standing for the whole log.

Can Estimated Weight Set Crane Or Trailer Capacity?

An estimated log weight should never determine crane or trailer capacity by itself. Load balance, lift angle, road law, moving force, gear limits, and operator competence need their own checks. Use a safe confirmed weight for final work.

Sources

Last updated: . Reviewed for accuracy against the formula shown above.