Board Feet vs Cubic Metres: Converting Timber Measurements
A cubic metre measures solid wood volume. A board foot log rule estimates the sawn output you would recover from a log — after saw kerf, slabs and edgings are lost.
They are not the same kind of number, which is why any single conversion factor is an approximation. And the three US log rules disagree with each other, sometimes substantially, on the same log.
Outside North America, sell in cubic metres. It is unambiguous.
They Measure Different Things
| Cubic metre (m³) | Board foot (log rule) | |
|---|---|---|
| Measures | Solid wood volume | Estimated sawn lumber recovery |
| Depends on saw technology? | No | Yes — kerf and milling practice are baked in |
| Ambiguity | None | Three competing rules give different answers |
| Definition | 1m × 1m × 1m of solid wood | 1ft × 1ft × 1in of sawn lumber |
| Used in | Most of the world | United States, parts of Canada |
One board foot is 144 cubic inches of lumber. One cubic metre is about 424 board feet of lumber — but that is a lumber-to-lumber conversion, not a log-scale conversion, and confusing the two is where most errors come from.
The Three US Log Rules
| Rule | Character | Effect |
|---|---|---|
| Doyle | BF = ((D − 4) / 4)² × L, D in inches (small end), L in feet | Severely under-scales small logs. A 10-inch log scales at roughly half what other rules give. Favours the buyer. |
| Scribner | Table-based, derived from diagrams of boards in a circle | Middle ground; under-scales small logs less than Doyle |
| International ¼-inch | Formula-based, allows for taper and a ¼-inch kerf | Most accurate estimate of actual recovery; generally the highest scale |
Why the rule matters commercially
- On the same log, Doyle and International can differ by a wide margin, and the gap widens as logs get smaller.
- Sellers of small timber prefer International; buyers often prefer Doyle. That is not a coincidence.
- Always establish which rule is being used before agreeing a price. "So many board feet" is meaningless without it.
- Our calculator implements Doyle only, because it is a clean formula. Scribner and International ¼-inch depend on published tables, and approximating them with a formula introduces error we are not willing to hide.
Converting Between Them
- Lumber: 1 m³ ≈ 424 board feet. This is solid-to-solid and is reliable.
- Logs: there is no single reliable factor, because the board-foot figure depends on which log rule and on log diameter. Rough working figures circulate (often in the range of 150–250 board feet per cubic metre of log), but they vary so much with diameter and rule that quoting one precisely would be misleading.
- Other units: 1 m³ = 35.31 ft³; 1 MBF = 1,000 board feet; 1 cord = 128 ft³ of stacked wood including air space, so it is not directly a solid-volume measure either.
Selling into an unfamiliar market? Agree the measurement convention first.
Which Should You Use?
- Outside North America: cubic metres. Unambiguous, internationally understood, independent of milling technology.
- Selling logs in the US: whichever rule the buyer uses — but know which it is and what it does to small logs before you agree a price.
- Selling sawn lumber anywhere: board feet or cubic metres both work, since you are measuring an actual product rather than estimating a recovery.
- Buying across a border: convert carefully, and state the convention in the contract. This is a routine source of dispute.
Frequently Asked Questions
How many board feet are in a cubic metre?
For sawn lumber, about 424 board feet per cubic metre — that is a solid-to-solid conversion and it is reliable.
For logs there is no single answer, because board-foot log rules estimate sawn recovery rather than solid volume, and the figure depends on which rule and on log diameter.
What is the difference between Doyle, Scribner and International rules?
All three estimate how much lumber a log will yield, but they disagree. Doyle severely under-scales small logs; Scribner sits in the middle; International ¼-inch is generally the most accurate estimate of actual recovery.
On the same small log the difference can be large, which is why you must establish the rule before agreeing a price.
Why does Doyle give such a low number for small logs?
Because of how the formula is constructed — ((D − 4) / 4)² × L — the deduction of four inches has a disproportionate effect at small diameters.
A 10-inch log can scale at roughly half what International gives. Sellers of small timber dislike Doyle for exactly this reason.
Should I sell timber in board feet or cubic metres?
Outside North America, cubic metres — unambiguous and independent of milling technology. Inside North America, use whichever rule the buyer uses, but know what it does to your size class.
For sawn lumber rather than logs, either works, because you are measuring a real product rather than estimating recovery.
Is a cord the same as a cubic metre?
No. A cord is 128 cubic feet of stacked wood including the air space between pieces, so it is not a solid-volume measure.
The solid wood in a cord varies with piece size and stacking quality, which is why cords are used for firewood rather than for timber sales.
Do Not Let the Units Cost You
Measurement conventions are a routine source of dispute in timber sales. We measure, document the method, and make it verifiable.
Over a decade establishing, measuring and managing eucalyptus, pine and indigenous plantations across Uganda. Based in Wakiso, Kampala. Reviewed and updated September 6, 2026.
Keep going
These apply the same way in any country.
