Board foot calculator for lumber and logs
This board foot calculator adds up the board feet in a list of lumber, scales logs by the Doyle, Scribner and International ¼-inch rules, and estimates the studs and plates for a framed wall. Enter pieces and sizes and it gives board feet, cubic metres and linear feet, and a cost if you enter a price per board foot, per thousand board feet (MBF) or per cubic metre.
Woodworkers pricing hardwood, builders ordering framing lumber, sawmill customers and woodlot owners use it as a board foot calculator for logs and boards alike. Sizes can be entered in inches and feet or in millimetres and metres, so it works for Canadian and Australian timber lists too.
All the arithmetic runs in your browser. Log rules estimate sawn yield, not a guarantee — defects, sweep and the mill's saw kerf change the real result.
How to use the Board Foot Calculator (Lumber & Logs)
- Choose Lumber list, Logs or Wall framing.
- For a lumber list, enter pieces, thickness, width and length for each size, or pick a common size such as 2 × 4 to add a row. Add a waste allowance if you like.
- For logs, measure the small-end diameter inside the bark and the length, enter the number of logs and pick a log rule — the table shows all three rules side by side.
- For wall framing, enter the wall length, stud spacing, stud size and length, extra studs for corners and openings, and the plate stock length.
- Add a price per board foot, MBF or m³ to see the cost, then copy the summary or download a CSV.
Board Foot Calculator (Lumber & Logs) features
Cut lists of any length
Add as many board sizes as you need; each row shows board feet per piece and per row.
Three log rules
Doyle, Scribner (Decimal C formula) and International ¼-inch, compared as a percentage of International.
Framing take-off
Studs at 12, 16 or 24 in on centre plus plates, in board feet and pieces.
Metric too
Millimetre and metre sizes convert to board feet, and every result shows cubic metres.
Three price bases
Per board foot for hardwood, per MBF for logs and framing, or per cubic metre.
How to calculate board feet
A board foot is 144 cubic inches — a piece 1 in thick, 12 in wide and 1 ft long. For any board, board feet = thickness (in) × width (in) × length (ft) ÷ 12.
Worked example: ten 2 × 4s 8 ft long are 10 × 2 × 4 × 8 ÷ 12 = 53.33 board feet, and four 1 × 6 boards 10 ft long add 4 × 1 × 6 × 10 ÷ 12 = 20, for 73.33 board feet in all. At $2.50 per board foot that is $183.33. One board foot is 0.00236 m³, so 1 m³ is about 424 board feet.
Softwood dimension lumber is counted on its nominal size (a 2 × 4 is really 1½ × 3½ in but is sold as 2 × 4). Hardwood is sold rough by the quarter-inch: 4/4 is 1 in thick, 5/4 is 1¼, 8/4 is 2 in, and board feet are figured on that rough thickness.
Log rules compared
Each rule uses the small-end diameter inside the bark (D, inches) and the log length (L, feet). Values for a 16 ft log:
| Small-end diameter | Doyle | Scribner (formula) | International ¼-inch |
|---|---|---|---|
| 8 in | 16 | 31 | 39 |
| 12 in | 64 | 86 | 97 |
| 16 in | 144 | 166 | 181 |
| 20 in | 256 | 272 | 290 |
| 24 in | 400 | 403 | 424 |
About the rules and the framing estimate
- Doyle = (D − 4)² × L ÷ 16. Simple and still common in the US South and East, but it under-scales small logs badly.
- Scribner was drawn as board diagrams; the formula (0.79D² − 2D − 4) × L ÷ 16 approximates the Decimal C table, which rounds to tens of board feet.
- International ¼-inch allows for taper (½ in per 4 ft) and a ¼-in saw kerf and is the closest to real mill yield. Formulas are from Cornell Cooperative Extension's "Tree and Log Scales" (checked 19 October 2026); published tables round to the nearest 5 or 10.
- The framing estimate is one stud per spacing plus one, plus the extras you enter; it does not lay out headers, cripples or blocking. For decking use the deck board calculator, for fences the fence calculator, and for the insulation between the studs the insulation calculator.
Board Foot Calculator (Lumber & Logs) FAQ
How do I use a board foot calculator for lumber?
Enter the number of pieces and the thickness, width and length of each size. The calculator multiplies thickness × width × length in feet and divides by 12 for each board, then adds them up.
How many board feet are in a 2 × 4 × 8?
A 2 × 4 that is 8 ft long has 2 × 4 × 8 ÷ 12 = 5.33 board feet, counted on its nominal size.
How do I calculate board feet in a log?
Measure the small-end diameter inside the bark and the length, then apply a log rule. A 16 in × 16 ft log scales 144 BF by Doyle, about 166 by the Scribner formula and 181 by International ¼-inch.
Which log rule should I use?
Use the one your buyer or mill uses — prices per MBF only make sense on the same rule. International ¼-inch is the most accurate for yield; Doyle is common for hardwood sales in many US states.
How much lumber do I need to frame a wall?
At 16 in on centre, a 20 ft wall needs 16 studs plus extras for corners and openings, and three plate lines (bottom and double top). With 92⅝ in precut 2 × 4 studs and 12 ft plates that is about 130 board feet.
How many board feet are in a cubic metre?
About 423.8. One board foot is 0.00235974 m³.