Timber Volume Calculator for sawn timber and round logs. Enter piece sizes, or log ends and middle, to see cubic feet, cubic meters, board feet and Hoppus feet for the entire load.
Width and thickness in inches, length in feet.
Nominal Size and Spare Pieces
Nominal lumber like a 2×6 is measured on its dressed size, as PS 20-25 requires.
Common Sizes at This Length
| Size | Each, cu ft | Per m³ | Per cu ft |
|---|---|---|---|
| 1×4 | 0.182 | 193.7 | 5.49 |
| 1×6 | 0.286 | 123.3 | 3.49 |
| 2×4 | 0.365 | 96.9 | 2.74 |
| 2×6 | 0.573 | 61.6 | 1.75 |
| 2×8 | 0.755 | 46.8 | 1.32 |
| 2×10 | 0.964 | 36.7 | 1.04 |
| 4×4 | 0.851 | 41.5 | 1.18 |
| 6×6 | 2.101 | 16.8 | 0.48 |
Nominal names with PS 20-25 dressed sizes. Pieces per m³ and per cu ft answer how many boards make one CBM or one CFT.
Your Volume in Every Unit
| Unit | Volume |
|---|---|
| Cubic Feet | 27.778 |
| Cubic Meters | 0.7866 |
| Board Feet | 333.3 |
| Liters | 786.6 |
1 m³ = 35.315 cu ft = 423.78 board feet = 27.74 Hoppus feet. Board feet are 1/12 cu ft each.
Timber Volume Calculator for Sawn Boards and Round Logs
Timber is bought and sold by volume in cubic feet, cubic meters, board feet or, for some hardwood logs, Hoppus feet. The Timber Volume Calculator works out that volume for a stack of sawn pieces or a load of round logs. It suits buyers checking a timber invoice, sawyers measuring logs before milling and anyone converting between CFT and CBM.
For sawn timber, enter the length in feet, the width and thickness in inches and the number of pieces. For round logs, enter the length and the small-end, large-end and middle measurements, as diameters or as girths taken with a tape. Metric units switch the inputs to millimeters, centimeters and meters.
Cubic Feet, Cubic Meters and Board Feet
Sawn timber volume is width times thickness times length. With the length in feet and the other two in inches, dividing by 144 gives cubic feet.
Divide by 1,728 only when all three measurements are in inches. Using 1,728 with the length in feet reads 12 times too low, which is the most common slip with this formula. In metric, width and thickness in millimeters times length in meters, divided by 1,000,000, gives cubic meters.
The default order is 25 pieces of 2 × 8 inch timber, 10 feet long. That totals 27.78 cubic feet, 0.787 cubic meters or 333.3 board feet, and about 31.8 of those pieces make one cubic meter. With a 10% spare rounded up to whole pieces, the order becomes 28 pieces and 31.11 cubic feet.
One cubic meter is 35.315 cubic feet, and each cubic foot holds 12 board feet. That puts 423.78 board feet in a cubic meter, the factor the Your Volume in Every Unit table uses alongside liters.
The fourth card adds the surface area of every face, which is what a stain, sealer or preservative has to cover. It lists the end grain separately, since the ends soak up the most finish.
Nominal Lumber Is Measured on Its Dressed Size
US softwood lumber carries nominal names, but cubic volume uses the size you can actually measure. The American Softwood Lumber Standard, PS 20, says dressed sizes are used when lumber is measured by cubic measure. Set Size Entered As to US Softwood Nominal and the tool swaps in the PS 20 dressed size.
Twenty-five nominal 2 × 8s, 10 feet long, then hold 18.88 cubic feet, not 27.78. The dressed 1-1/2 by 7-1/4 inch section is 32% smaller than the nominal 2 by 8.
Some cubic meter calculators tell you to use the nominal width and thickness, which is not how PS 20 measures US softwood. Board feet still follow the nominal size, because that is how softwood lumber is billed. For pricing on either basis, the Timber Cost Calculator converts a quote into every unit.
Round Log Volume by Smalian, Huber and Newton
A log narrows from butt to top, so no single diameter gives its volume. Forest mensuration uses three classic formulas. Each one treats the log as a solid of revolution and averages cross-section areas in a different way.
As, Am and Al are the cross-section areas at the small end, middle and large end, and L is the length. The University of Göttingen forestry wiki notes all three are exact for a paraboloid log and Newton's is also exact for a cone.
On a cone-shaped log, Smalian's formula reads high and Huber's reads low by half as much. A 2013 study in the journal Bosque confirms that Huber's error is exactly half of Smalian's, with the opposite sign.
The default log shows it. At 12, 14 and 16 inches over 10 feet, Newton gives 10.76 cubic feet. Smalian reads 1.35% higher and Huber 0.68% lower. A cylinder sized from the large end would read almost 30% high, the most common overestimate of all.
Smalian is still the most widely used because it only needs the two ends. Brack and Wood's forest mensuration notes call it the easiest to apply but the least accurate, especially on flared butt logs. An article in The Forestry Chronicle says Canadian scalers use it for most logs but that it severely overstates the first log above the stump.
The tool warns when the middle falls outside the two ends, a sign of butt swell or a knot at mid-length. In that case, measure the middle where the stem is smooth, or switch the headline to Smalian.
Log scales count wood inside the bark, so enter the bark thickness on one side if your tape went over it. The tool takes twice that off every diameter. For sawn board feet from the same logs, the Lumber Yield Calculator applies the Doyle, Scribner and International log rules.
Hoppus Feet and the Quarter Girth Rule
The first card on the log side gives the Hoppus volume. It was the timber measure of the British Empire and is still used in parts of the hardwood trade, with some Myanmar teak shipments stated in Hoppus tons.
G is the mid-length girth in inches and L is the length in feet. A UK Workshop forum example works a 16 foot log with a 69 inch girth to 33.06 Hoppus feet, or about 42.1 true cubic feet.
Hoppus volume is 78.5% of the true round volume, so it reads 21.5% low. One Hoppus foot equals 1.273 cubic feet, which is where the 27% figure some sources quote comes from, read in the wrong direction. One cubic meter equals 27.74 Hoppus feet.
Timber Volume Questions
How many boards are in one cubic meter?
Divide 1 by the volume of one board in cubic meters. A dressed 2 × 4 that is 10 feet long holds 0.365 cubic feet, so about 96.9 of them make a cubic meter. The same length of 2 × 8 comes to about 46.8.
The Common Sizes at This Length table lists pieces per cubic meter and per cubic foot for eight standard sizes, using the length you entered. For the weight of that volume by species, see the Wood Weight Calculator.
How do I measure girth for a log?
Wrap a tape around the log at the point you are measuring, square to its length. Set Measure Logs By to Girth and the tool converts each girth to a diameter by dividing by pi.
For Hoppus volume, measure at mid-length. For Smalian, Huber and Newton, measure both ends and the middle, avoiding knots and butt flare. A tape laid over rough bark reads large, so enter the bark thickness to get wood only.