Enter the trunk radius and trunk height (or the length of the trunk section) into the Tree Volume Calculator to estimate volume using a cylindrical approximation. Real tree stems taper, so this method will typically overestimate true stem volume unless a taper/form factor model is used.

Tree Trunk Volume (Cylindrical Approximation) Calculator

Measure the trunk once with a tape, enter the length, get the volume.

Around the trunk (tape)
Across the trunk (diameter)

Related Calculators

Tree Trunk Volume (Cylindrical Approximation) Formula

This calculator estimates the volume of a tree trunk or log section by modeling it as a right circular cylinder. It is most useful when you need a fast volume estimate for timber checks, firewood planning, biomass comparisons, transport planning, or general material estimation.

TV = \pi \cdot TR^2 \cdot TH
  • TV: estimated trunk volume
  • TR: trunk radius
  • TH: trunk height or trunk section length being modeled

If you measured diameter instead of radius, convert diameter first:

TR = \frac{D}{2}

If you measured circumference around the trunk, convert circumference to radius:

TR = \frac{C}{2\pi}

You can also express the same volume relationship directly in terms of diameter:

TV = \frac{\pi \cdot D^2 \cdot TH}{4}

How to Measure for the Calculator

Input How to Measure It Why It Matters
Trunk radius Measure trunk diameter across the section you care about, then divide by two. Radius drives the cross-sectional area, so small diameter errors can create large volume errors.
Trunk height or length Use the actual length of the trunk section, log, or merchantable stem segment being estimated. The calculator assumes that the measured radius continues through the full modeled length.
Units Keep both measurements in the same unit before calculating. Consistent units prevent distorted results.

For standing trees, many users measure diameter at breast height and then pair that measurement with an estimated merchantable height. This is convenient, but it usually produces a higher volume than the true stem volume because real trunks narrow as height increases.

Unit Guidance

  • If radius and height are entered in feet, the result is in cubic feet.
  • If radius and height are entered in meters, the result is in cubic meters.
  • If radius and height are entered in centimeters, the raw result is in cubic centimeters.
  • If radius and height are entered in inches, the raw result is in cubic inches.

Helpful conversions for interpreting the result:

  • One cubic foot corresponds to about 28.3168 liters.
  • One cubic meter corresponds to 1,000 liters.
  • One cubic meter corresponds to about 35.3147 cubic feet.

Examples

Example 1: Radius and length in feet

A trunk section with a radius of 1.5 feet and a length of 20 feet has an estimated volume of:

TV = \pi \cdot 1.5^2 \cdot 20 \approx 141.37

The estimated trunk volume is about 141.37 cubic feet.

Example 2: Diameter-based estimate

If a log has a diameter of 24 inches, its radius is 12 inches. For a log length of 96 inches:

TV = \pi \cdot 12^2 \cdot 96 \approx 43429.38

This corresponds to about 43,429.38 cubic inches, or about 25.13 cubic feet after conversion.

Why This Calculator Is an Approximation

A cylinder model is simple and fast, but real trees are not perfect cylinders. The estimate can differ from actual wood volume because of:

  • natural trunk taper from base to top
  • butt swell near the base
  • elliptical or irregular cross-sections
  • bark thickness
  • hollows, rot, and internal defects
  • crook, flare, or swelling around knots and branch zones

The estimate is typically most accurate for short, fairly uniform log sections and least accurate for full standing trunks with noticeable taper.

Adjusting for Taper or Form Factor

If you already know a local form factor or a forestry adjustment factor for the species and measurement method you are using, you can scale the cylindrical estimate:

TV_{adj} = f \cdot \pi \cdot TR^2 \cdot TH

In this expression, f is an adjustment factor that reduces the pure cylinder estimate to better reflect the shape of an actual trunk.

When to Use This Calculator

  • Estimating the volume of a cut log section
  • Comparing trunk sizes across multiple trees
  • Planning hauling space or storage capacity
  • Approximating stem wood volume for inventory work
  • Checking whether a measured trunk section is in a reasonable range before using more advanced forestry rules

Practical Tips for Better Results

  • Measure diameter in two directions at right angles and average the readings when the trunk is not perfectly round.
  • Decide whether you are measuring inside bark or outside bark, then stay consistent.
  • For logs, use the actual usable log length rather than a rough visual estimate.
  • For standing trees, estimate only the trunk section you truly want to model instead of assuming the same diameter all the way to the tip.
  • If you need a commercial log scale rather than a pure geometric volume, use a dedicated log rule calculator.

Common Questions

Can I use diameter instead of radius?
You can. Measure diameter and divide by two before entering the value, or use the diameter form of the equation shown above.

Can I use circumference instead of diameter?
Yes. Convert circumference to radius first, then calculate volume.

Does this include branches, roots, or foliage?
No. This calculator estimates only the trunk or trunk section you model.

Why does my result seem too large for a standing tree?
The cylinder method assumes the same trunk thickness across the full height or length entered. Since most trunks taper, full-tree estimates are often higher than the actual stem volume.