Log Weight Calculator

Estimate a log or board's weight from species, density and dimensions.

Covers 65 green densities, both shapes, and piece or stack counts in either unit system.

Updated October 22, 2026

CreatorFrank Zhao

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Introduction

A freshly cut log is heavy, and much of that weight is water. This calculator turns the species and a handful of measurements into the green weight of one log or board, then into the total for a batch you can count or a pile you can measure.

It is the number you want when a weighbridge is not available: what a trailer is about to carry, what a crane has to lift, what a load of green timber comes to at a price per metric ton, or whether a pile is worth moving in one trip. The answer follows the measurements you actually took, so a short, thick butt log and a long, slender pole are treated as the different pieces of wood they are.

The two answers most people leave with are the weight of one piece and the weight of the load. Everything between them — volume, the mid-section diameter, the number of pieces in a pile — is there so you can check the number against the measurements instead of trusting a single figure.

Weight is about the wood, not the shape

Two piles of the same size are not two piles of the same weight. White oak is tabulated at about 993 kg/m³ and willow at about 513 kg/m³, so the same volume is roughly twice as heavy in oak. Changing the species changes the answer without a single dimension moving.

Quick start

Four choices take you from a tree on the ground to a load weight. The example below is the same one you can reproduce on the page.

Choose the species

The density box fills in from the species table. The figures are green densities — the weight of freshly felled wood that still holds its moisture. If your timber has dried, or your supplier quotes a density of their own, choose the custom entry at the end of the list and type that number instead.

Pick the shape and enter the measurements

For a log, enter the diameter at both sawn ends and the length. The diameter halfway along is worked out for you. For a board, enter its width, thickness and length. Length can be typed as feet and inches when that is what the tape shows.

Read the per-piece answer

Volume and weight per piece appear as soon as the measurements are complete. This is the weight of one log or board at the chosen density, before any count is applied.

Say what you know about the load

If you know how many pieces there are, enter the count. If the timber is in a pile, choose stack dimensions and measure the outside width and height. Either way the total weight is the last figure to read.

A worked log, step by step

Take a white oak log with a 28 cm top and a 34 cm butt, 2.5 m long. White oak sits at about 993 kg/m³ in the species table. First the average diameter:

d_{\mathrm{m}}

=

\frac{28 + 34}{2} = 31\ \mathrm{cm}

That 31 cm goes into Huber's formula, with the length in meters:

V

=

\frac{\pi \times 0.31^{2} \times 2.5}{4} = 0.1887\ \mathrm{m^{3}}

Multiply by the density and the piece weight comes out at:

W

=

993.144729 \times 0.1887

=

187.4\ \mathrm{kg}

The page keeps more digits than the rounded figures above: 0.18869190876 m³ of volume and 187.39837459 kg for the piece. Use the shorter numbers when you only need a sensible estimate, and the page figures when you are comparing against a scale.

Now suppose those logs are piled 3.0 m wide and 1.5 m high. The pile is nine logs across and five nested rows high — the rows sit in the gaps between the logs below, so it holds more than a straight grid of nine columns by four rows would:

\left\lfloor \frac{3.0}{0.31} \right\rfloor

=

9\ \text{columns}

\times

5\ \text{rows}

=

45\ \text{logs}

Forty-five logs at 187.4 kg each is about 8,433 kg — the page reads 8,432.9268564 kg — or roughly 8.43 metric tons. That is the number to compare with the trailer's rated payload.

What each result means

Result	What it tells you
Volume	The space one piece occupies. It is also the box that can be typed in to work a length or a diameter back out.
Weight per piece	The mass of a single log or board at the chosen density. It is a result, not an input.
Quantity in stack	How many complete pieces the pile is estimated to hold. Partial pieces and the leftover width are not counted.
Total weight	The per-piece weight times the count, or the pile estimate. This is the transport figure.

How the weight is calculated

A diameter average, a volume and a density sit behind every number. The volume and weight are computed from your measurements and the chosen density, not copied from a table of pre-weighed logs.

The density is green density

Fresh wood is largely water — often half its mass or more — and the species table gives the density of that fresh state. It is why the same log weighs noticeably less once it has dried; the second worked example puts the difference at about a quarter of the green weight. If your question is about dried timber, the species table will overstate the weight — switch to the custom density and use the figure from your supplier, your moisture meter or your own dry-weight measurement.

Log volume: Huber's formula

The log is treated as a cylinder whose diameter is the one measured halfway along its length. Averaging the two ends is how you find that diameter when you cannot measure the middle directly:

d_{\mathrm{m}} = \frac{d_{\mathrm{s}} + d_{\mathrm{l}}}{2}

V = \frac{\pi\,d_{\mathrm{m}}^{2}}{4}\,L

A board is simpler — three measurements multiplied together, with no taper to average:

V = w \times t \times L

Weight and load total

W = \rho \times V

W_{\mathrm{total}} = n \times W

Counting a pile

Boards stack in solid rows, so the count is the whole pieces across times the whole thicknesses up, with both divisions rounded down:

n_{\mathrm{stack}}

=

\left\lfloor \frac{W_{\mathrm{s}}}{w} \right\rfloor

\times

\left\lfloor \frac{H_{\mathrm{s}}}{t} \right\rfloor

Logs are different: each row drops into the hollows of the row below. The width left over after the last full column sets how far a column can nest, and a pile is never allowed to pack tighter than a hexagonal arrangement:

n_{\mathrm{stack}}

=

\left\lfloor \frac{W_{\mathrm{s}}}{d_{\mathrm{m}}} \right\rfloor

\left( \left\lfloor \frac{H_{\mathrm{s}} - d_{\mathrm{m}}}{d_{\mathrm{m}}\sin\theta} \right\rfloor + 1 \right)

\cos\theta

=

\frac{r}{d_{\mathrm{m}}}

\qquad \sin\theta \ge \sin\frac{\pi}{3}

The $+1$ is the bottom row, which always fits. The clamp at $\sin(\pi/3)$ is what stops a nearly complete column from pretending its rows could touch.

Which boxes can be an answer

Volume is deliberately editable. Measure a pile of offcuts, read a volume off a displacement test, or divide a target weight by the density and enter the result. With the length or one diameter already measured, the page then works the missing dimension back out. Weight and total weight are the opposite: they are answers, so they cannot be typed in and cannot rewrite a density or a dimension. If a target weight is your starting point, convert it first:

V

=

\frac{W_{\mathrm{target}}}{\rho}

If the log is going to be sawn, the next question is board feet rather than kilograms. The Board Foot Calculator converts cut dimensions and lengths into board feet, while this page stays with the mass of the wood.

d_{\mathrm{s}}

Diameter at the smaller, top end of the log

d_{\mathrm{l}}

Diameter at the larger, butt end

d_{\mathrm{m}}

Diameter halfway along, the one the volume uses

L

Length of the log or board

V

Volume of one piece

w

Width of a board

t

Thickness of a board

\rho

Green density of the chosen species

W

Weight of one piece

n

Number of pieces

W_{\mathrm{s}}

Outside width of the stack

H_{\mathrm{s}}

Outside height of the stack

\theta

Nesting angle between one row of logs and the row below

r

Width left over after the last complete log column

Worked examples

Two situations the calculator is commonly used for: a pile of sawn boards waiting for a trailer, and the same log weighed green versus dry.

A stack of boards for a deck

Situation: A yard has a pile of white oak boards, each 20 cm wide, 5 cm thick and 2.4 m long, stacked 2.4 m wide and 1.2 m high. The buyer wants to know whether one trailer can take the pile.

Inputs

SpeciesOak, white

Board20 cm wide, 5 cm thick, 2.4 m long

Stack2.4 m wide, 1.2 m high

Density993.144729 kg/m³ (green)

Result

V

=

0.20 \times 0.05 \times 2.4

=

0.024\ \mathrm{m^{3}}

W

=

993.144729 \times 0.024

=

23.8355\ \mathrm{kg}

n_{\mathrm{stack}}

=

12 \times 24

=

288\ \text{boards}

W_{\mathrm{total}}

=

288 \times 23.8355

=

6,864.6\ \mathrm{kg}

In practice: If the trailer is rated at 3.5 metric tons, this pile is about twice its limit: it needs two trips, or a lighter selection.

The same log, green and dry

Situation: A woodworker wants to quote on the 2.5 m white oak log from the quick start, but sells dried stock and knows from a moisture reading that the supplier's dry density is about 750 kg/m³.

Inputs

SpeciesOak, white, then custom density

Measurements28 cm top, 34 cm butt, 2.5 m long

Green density993.144729 kg/m³

Dry density750 kg/m³ (supplier figure)

Result

W_{\mathrm{green}}

=

993.144729 \times 0.1887

=

187.4\ \mathrm{kg}

W_{\mathrm{dry}}

=

750 \times 0.1887

=

141.5\ \mathrm{kg}

The difference — about 46 kg, or a quarter of the green weight — is water that leaves the wood as it dries. That is why a dried load can be quoted at the same price per cubic meter and still weigh far less on the road.

In practice: Use the green figure for transport and fresh-timber pricing, and the dry figure for dried stock quotes. The geometry does not change — only the density behind it does.

Measuring for a reliable answer

The formulas are straightforward; the measurements are where most of the error comes from. These habits keep the answer close to a real scale.

Measure the middle, or average both ends

Huber's formula wants the diameter halfway along. If the middle of the log is easy to reach, measure it there and enter it directly. If not, measure across both sawn ends and let the average stand in for it.

Turn a tape circumference into a diameter

A tape wrapped round the log reads circumference, not diameter. Divide that reading by $\pi$ — about 3.14 — before entering it. For example, 97 cm round is a 31 cm diameter.

Keep bark and length conventions consistent

A diameter that includes the bark gives a larger volume than one measured under it, and a length that includes the unusable top does the same. Measure the way your buyer or your own records do, and use the same convention every time.

Measure the pile at its widest point

Stack width and height are outside measurements, taken at the widest and highest points of the pile. A loosely thrown pile has more air and fewer pieces than the count suggests, so measure a neat stack or expect the estimate to run high.

Use whole pieces for a count

The quantity box accepts any value of 1 or more, so a fraction still produces a total — but half a log is not a thing you can load. Enter whole pieces, and remember that the stack count already rounds down to complete pieces.

Compare two species before you buy

If two species are available, run the same measurements through both. The volume will not change; the weight can differ by more than double, and that difference is the price of a second trailer.

Oval logs and fluted trunks

A log is treated as round. An oval cross-section or a fluted trunk can measure one diameter that fits the average while holding less wood than a true cylinder. When the shape is obviously irregular, take one diameter across the wide axis and one across the narrow axis, average them, and treat the result as a careful estimate rather than a measurement.

Questions

Why does a fresh log weigh more than the same timber after drying?

The species densities here are green densities: they describe wood straight from the tree, still carrying a large share of water. As the wood dries, that water leaves and the mass drops, even though the piece is still the same log. If you are weighing dried stock, choose the custom density and enter your supplier's or your own measured figure.

Can I type in a target weight and get the length or diameter?

Not directly — weight and total weight are results and stay read-only. Convert the target into a volume first by dividing the weight by the density, then enter that volume with the length or one diameter already in place, and the page will solve the missing one.

V

=

\frac{W_{\mathrm{target}}}{\rho}

Why does the stack count not match rows times columns?

Log rows nest into the hollows below them, so a pile usually holds more rows than its height divided by one diameter suggests. At the same time both divisions round down to complete pieces, and the width left over after the last full column limits how far the rows can nest. Boards behave differently again: they stack in solid rows of full thickness. Treat the count as a packing estimate, not a tally.

Is this the same as board feet or a timber cruise?

No. Board feet measure sawn volume, and a timber cruise estimates recoverable lumber from standing trees with its own grading rules. This page estimates the mass of the wood you can see and measure, so a sawn-volume figure and a green-weight figure will never be the same number.

Where the estimate stops

The answer is a good estimate of the wood you described, not a certified weight. These are the assumptions worth knowing before you quote, load or bill anyone.

•Species figures are averages. Site, age, heartwood and sapwood all move the density of an individual log. Two white oak logs of the same size can differ noticeably on a scale.
•Moisture is the largest variable. The green densities assume freshly felled wood. Dry, seasoned or soaked timber will weigh something else — use the custom density for a figure you can stand behind.
•The geometry is simplified. Logs are treated as circular, boards as true rectangles. Rot, hollows, knots, bark thickness and a strongly oval cross-section are not detected, and a hollow log will weigh less than this estimate.
•Pile counts are packing estimates. They assume equal-sized pieces in a neat pile and round down to complete pieces. Crossed logs, wedged pieces and air gaps can move the real count either way.
•It is not a timber cruise or a valuation. Log rules, grade recovery and local scale conventions are separate questions, and this page does not answer them.

Check the load rating before you trust the total

A calculated total is not a permit to load it. Rated payload, axle limits, load distribution and local transport rules still decide what a vehicle may carry, and a weighbridge is the only figure a carrier should sign against. Use this estimate to plan and to catch a load that is obviously too heavy, then confirm it with a scale.

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