The rules disagree most on small logs: Doyle underestimates them heavily, while International ¼-inch is closest to what a modern mill actually saws.
How board feet are calculated
BoardFootCalc multiplies thickness (inches) × width (inches) × length (feet) and divides by 12 for each row, then multiplies by the quantity and adds the rows. Cost is total board feet × your price per board foot. Cubic feet are board feet ÷ 12, and cubic metres use 1 board foot = 0.00236 m³. Nothing is rounded until the result is shown.
Common lumber sizes
| Nominal | Actual (in) | Board feet per 8 ft |
|---|---|---|
| 1×4 | ¾ × 3 ½ | 2.67 |
| 1×6 | ¾ × 5 ½ | 4 |
| 1×8 | ¾ × 7 ¼ | 5.33 |
| 1×12 | ¾ × 11 ¼ | 8 |
| 2×4 | 1 ½ × 3 ½ | 5.33 |
| 2×6 | 1 ½ × 5 ½ | 8 |
| 2×8 | 1 ½ × 7 ¼ | 10.67 |
| 2×10 | 1 ½ × 9 ¼ | 13.33 |
| 2×12 | 1 ½ × 11 ¼ | 16 |
| 4×4 | 3 ½ × 3 ½ | 10.67 |
| 6×6 | 5 ½ × 5 ½ | 24 |
Actual sizes are dry dressed sizes from the American Softwood Lumber Standard (PS 20). Board feet use nominal size, as most lumberyards tally softwood.
Log rules for a 16-foot log
| Diameter (in) | Doyle | Scribner | International ¼″ |
|---|---|---|---|
| 8 | 16 | 31 | 39 |
| 10 | 36 | 55 | 65 |
| 12 | 64 | 86 | 97 |
| 14 | 100 | 123 | 136 |
| 16 | 144 | 166 | 181 |
| 18 | 196 | 216 | 232 |
| 20 | 256 | 272 | 290 |
| 24 | 400 | 403 | 424 |
| 28 | 576 | 559 | 584 |
| 32 | 784 | 741 | 770 |
Doyle: (D − 4)² × L ÷ 16. Scribner: the common formula approximation (0.79D² − 2D − 4) × L ÷ 16, so it can differ by a few board feet from the official Scribner tables. International ¼″: Grosenbaugh's formula. All are estimates of sawn yield, not a measurement of the log's volume.
Tips for buying lumber
Measure the finished parts you need, then add allowance for planing, defects and saw kerf. Rough hardwood is usually tallied by the dealer at the rough size, and widths are often rounded to the nearest inch. Prices per board foot vary widely by species, grade and region, so use your supplier's price.
Frequently asked questions
Which log rule should I use?
The one your buyer uses. Doyle is common in the US South and Midwest for hardwood, Scribner in the West, and International ¼-inch in some northern states and for research.
Why is Doyle so low for small logs?
Its formula subtracts 4 inches from the diameter for slab and sawdust, which is too much for small logs.
Where do I measure the diameter?
Inside the bark at the small end of the log, rounded down to the inch.
Is BoardFootCalc free?
Yes, with no sign-up or ads.
Is my cut list saved?
Yes, in this browser only.