Log Board Foot Calculator
Estimate board-foot yield from round logs using small-end diameter inside bark, log length, quantity, log rule, and defect deduction.
This page is for round logs before milling. If you already have boards or dimensional lumber, use the Board Foot Calculator.
Results
This estimates board-foot yield from a round log. It is not a guaranteed sawmill tally or timber appraisal.
How to use this calculator
- 01Choose Doyle, Scribner, or International 1/4-inch log rule.
- 02Enter log length and the small-end diameter inside bark.
- 03Enter quantity and any rough defect or deduction percentage.
- 04Open Add cost estimate only if you want a simple value from price per board foot.
Use the Log Weight Calculator when weight is the main question. Use the Firewood Calculator for cords, face cords, ricks, and loose firewood volume.
Understanding the math
Log board feet estimate how much usable lumber a round log may produce. Log rules use the small-end diameter inside bark and log length. Doyle, Scribner, and International 1/4-inch can give different answers for the same log.
D = small-end diameter inside bark, inches L = log length, feet
Doyle BF = ((D - 4)^2 x L) / 16
Scribner BF = ((0.79 x D^2) - (2D) - 4) x (L / 16)
adjusted_board_feet = total_board_feet x (1 - deduction_percent / 100) estimated_value = adjusted_board_feet x price_per_board_foot
The International 1/4-inch result uses an integrated formula estimate. Real recovery can change with defect, taper, sweep, kerf, species, sawmill setup, and log quality.
Log rule reference
Compare common log rules using the active unit example. The calculator keeps board feet as the output unit because log scaling rules are board-foot rules.
| Log rule | Example yield | Behavior |
|---|---|---|
| Doyle | 32 BF (12 in inside bark x 8 ft) | Lower on small logs. |
| Scribner | 42.9 BF (12 in inside bark x 8 ft) | Diagram-based sawlog rule. |
| International 1/4-inch | 44 BF (12 in inside bark x 8 ft) | Closer recovery estimate. |
Frequently asked questions
How do you calculate board feet on a log?
Log board feet are estimated from small-end diameter inside bark, log length, and a log rule such as Doyle, Scribner, or International 1/4-inch.
What log diameter should I use?
Use the small-end diameter inside the bark. If the log end is not round, measure two directions and use the average.
What is the difference between Doyle, Scribner, and International log rules?
They are different scaling rules, so they can return different board-foot estimates for the same log. Doyle often reads lower on small logs, while International 1/4-inch is often closer to expected sawmill recovery.
Why do log board foot estimates vary?
Defect, taper, sweep, kerf, sawmill setup, species, and log quality can all change real lumber recovery.
How many board feet are in a 16 ft log?
It depends on the small-end diameter and selected log rule. Enter 16 ft length and the small-end diameter to estimate the board feet.
Is this the same as a regular board foot calculator?
No. This calculator estimates board feet from a round log using log rules. A regular board foot calculator is for rectangular boards using thickness, width, and length.
Can I use this calculator with metric measurements?
Yes. Use the Imperial/Metric toggle. Inputs, examples, and reference values follow the active unit system where applicable, while board feet remain the main output unit.
Related calculators
Board Foot Calculator
Calculate board feet, lumber volume, and optional cost for dimensional lumber and rough-sawn boards.
Log Weight Calculator
Estimate round log weight from length, diameter, taper, quantity, species, and wood condition.
Firewood Calculator
Estimate stacked firewood cords, cord of wood volume, loose firewood volume, face cords or ricks, planning quantity, and optional cost.