Measuring log volume: Huber and Smalian

Why volume is calculated

A round log is bought and sold by volume. Because a log is not a perfect cylinder, the result depends on the formula and on where the diameter is measured.

Huber

Huber uses the diameter at the middle of the log:

V = π/4 × d² × L

With a middle diameter of 30 cm and a length of 4 m, the volume is about 0.283 m³. Use consistent units: diameter in metres inside the formula (0.30 m), length in metres.

Smalian

Smalian averages the cross-section areas of both ends:

V = π/8 × (d₁² + d₂²) × L

For a log with a strongly tapering shape, Smalian tends to give a larger value than Huber, because the average of two end areas is larger than the area at the middle diameter of a cone-like log.

What to watch for

• Diameters are normally taken under bark. Agree with the buyer whether bark is deducted.
• Many markets sort and pay by top diameter and length classes, not by a formula. The contract rule always wins.
• Defects such as sweep, rot or forks are not reflected in these formulas.

You can try both formulas with the Log volume calculator.