Introduction
Two logs with identical diameters and lengths can be worth wildly different amounts. Species sets the price level, diameter sets the grade potential, and defects – rot, sweep, knots, embedded metal – decide how much of the scaled volume is payable. The board-foot formulas assume a sound, straight log; this guide is about judging how close a real log comes to that assumption before you price it, buy it, or mill it.
The Log Board Feet Calculator computes Doyle, Scribner, and International 1/4-inch board footage from diameter and length – the volume side of every log decision. This guide covers the material side: which species suit lumber, how quality is graded, which defects kill value, and how bark, moisture, and log condition affect the number you can trust. Pair it with the estimating guide for measurement technique.
Hardwood vs Softwood for Lumber
The first split in log value is botanical. Hardwoods (oak, walnut, cherry, maple) come from broadleaf trees and generally produce denser, higher-value lumber for furniture, flooring, and cabinetry. Softwoods (pine, fir, spruce, cedar) come from conifers and dominate construction framing, where volume matters more than figure.
Hardwood log trade typically runs on the Doyle scale in the eastern US; softwood trade typically runs on Scribner in the West. Species sets the per-MBF price band: commodity softwood logs trade at roughly $250-$500 per MBF, standard hardwoods at $400-$800, and premium hardwoods at $800-$1,500+ – all typical planning ranges that vary by region and market. The cost guide details pricing structure.
Common Lumber Species and Their Character
| Species | Type | Log character | Typical use |
|---|---|---|---|
| Red / white oak | Hardwood | Straight, large diameters common | Flooring, furniture, cabinetry |
| Black walnut | Hardwood | Moderate diameter, high figure value | Furniture, gunstocks, veneer |
| Black cherry | Hardwood | Straight, prized color | Cabinetry, furniture, millwork |
| Hard / soft maple | Hardwood | Clean, light-colored wood | Flooring, butcher block, furniture |
| Yellow poplar | Hardwood | Tall, straight, fast-grown | Paint-grade millwork, pallets |
| Southern yellow pine | Softwood | Abundant, smaller diameters | Framing, decking, posts |
| Douglas fir | Softwood | Large, straight, strong | Structural framing, timbers |
| Eastern red cedar | Softwood | Small diameter, aromatic | Closet lining, outdoor projects |
Species identification matters at purchase: a seller calling a log “walnut” should be able to show the bark and end grain to prove it. Confirm the species before agreeing to a premium price – misidentified logs are a classic and expensive mistake.
Log Quality and Grade
Mills grade logs on the quality of the lumber they will produce. The key quality factors:
- Straightness: straight logs yield long, clear boards; sweep (sideways curve) wastes wood and limits board length.
- Diameter: larger logs yield wider boards and higher grades. A 20-inch (51 cm) oak log can produce wide clear stock; a 12-inch (30 cm) log mostly produces narrow common lumber.
- Clear wood: sections free of knots and defects produce the highest-value boards. The outer clear shell of a large log is where the money is.
- Soundness: no rot, shake (separation along growth rings), or insect damage in the merchantable portion.
Grade names (veneer, sawlog grades 1-3, pallet/cant) vary by region and buyer, but the principle is universal: straight, large, clear, and sound commands the top per-MBF rate, and each defect steps the log down a grade. Get the buyer’s grade definitions in writing.
Defects That Reduce Value
The board-foot formulas assume a perfect log. Real logs carry defects that reduce payable volume, and professional scaling deducts for them. The common ones:
| Defect | What it is | Effect on value |
|---|---|---|
| Center rot / heart rot | Decay in the log’s center | Severe – can hollow the best wood; sound with a hammer (dull thud = decay) |
| Sweep | Sideways curve along the length | Moderate – reduces clear board length; scaled by deducting the curved portion |
| Knots and branches | Branch stubs in the wood | Mild to moderate – lowers grade; large or numerous knots drop the log a grade |
| Splits and checks | Cracks from felling or drying | Moderate – end splits trim off length; deep checks ruin boards |
| Embedded metal | Nails, wire, fence hardware in yard trees | Severe – one nail can destroy a saw blade; many mills reject or heavily discount yard trees |
| Shake | Separation along growth rings | Severe – boards fall apart at the separation; often renders the log unmerchantable |
Yard and fence-row trees deserve special suspicion for metal: decades of nails, clothesline hardware, and survey markers hide inside otherwise beautiful logs. A handheld metal detector ($30-$100) is cheap insurance before milling or selling a yard tree – which is why many mills discount urban logs regardless of species.
Bark, Moisture, and Log Condition
Bark contributes nothing to board footage – always scale inside it – but bark condition tells you about the log. Tight, intact bark on a fresh log is good; loose, slipping bark suggests the log has been down a while and may harbor decay.
Fresh vs. aged logs: freshly felled logs mill cleanly but the lumber needs 6 to 12 months of drying. Logs left on the ground for a year or more may have end rot, insect galleries, and checking that reduce yield. End-sealing fresh logs with anchor seal or latex paint slows checking dramatically and costs almost nothing.
Moisture and weight: a green 16-inch by 12-foot oak log weighs roughly 1,200 to 1,500 pounds (540 to 680 kg) – solidly “machinery or many helpers” territory. Weight also matters for transport regulations, covered in the code compliance guide.
Worked Example: Grading Changes the Number
Take a 16-inch, 12-foot red oak log: Doyle = (16 – 4) squared x 12 / 16 = 108 BF. At a standard-hardwood price of $600 per MBF, gross value is about $64.80. Now apply material judgment:
- Sound and straight: full 108 BF payable – about $64.80.
- Moderate sweep: a scaler might deduct 15 percent for the curved portion – about 92 BF, or $55.20.
- Center rot in the butt log: could easily deduct 30 to 50 percent – 54 to 76 BF, or $32 to $46.
- Embedded metal found: many mills reject the log outright or price it as pallet stock at $150-$350 per MBF – perhaps $16 to $38.
The formula gives 108 BF in every case; the material determines how much of it is real. This is why the pro tips guide insists on grading before pricing – the tape measure gives the gross, but only inspection gives the net.
Related Guides
- Complete Guide – log board feet basics, the three scales, and a full worked example.
- Cost Guide – typical log prices per MBF and what moves them up or down.
- Estimating Guide – how to measure diameter and length accurately in the field.
- Pro Tips – practical advice for buying, scaling, and milling logs.
- Common Mistakes – the errors that distort scale results, with fixes.
- DIY vs Pro – when to mill it yourself and when to hire a sawyer.
Frequently Asked Questions
Which species are most valuable as logs?
Black walnut, black cherry, and white oak typically command the highest per-MBF prices, especially in veneer grades. Standard hardwoods like red oak and maple sit in the middle; commodity softwoods and pallet-grade logs trade lower. All prices vary by region.
How much does rot reduce a log’s value?
It depends on extent: minor end rot trimmed off costs little, while center rot through the merchantable section can deduct 30 to 50 percent or more of scaled volume. Sound the log with a hammer and inspect the ends before pricing.
Are yard trees worth milling?
Sometimes – they are often large, open-grown trees with character – but embedded metal is the great risk. Scan with a metal detector first; many commercial mills discount or refuse urban logs for exactly this reason.
Does bark thickness affect the board-foot estimate?
Only if you measure outside it. Scales are defined inside the bark, so bark never contributes volume – but failing to exclude it inflates every estimate.
How long can a log sit before milling?
Mill promptly when possible. End-seal fresh logs immediately; logs left on the ground for many months develop end rot, checking, and insect damage that reduce yield.
What log size is best for milling lumber?
Logs 16 inches (41 cm) and up mill most efficiently into wide boards; 12 to 16-inch logs yield narrower stock; under 12 inches the yield per hour of milling drops sharply. Lengths of 8 to 16 feet suit standard lumber sizes.
Get Your Number
Inspect every log for rot, sweep, knots, and metal; sort by species and size; then run the measurements through the Log Board Feet Calculator for the board footage each log represents. Gross volume from the calculator, net value from your eyes: that combination is what fair log deals are built on.
Disclaimer: Calculator results are planning estimates based on the dimensions you enter and assume sound, straight logs. Actual lumber recovery varies with species, log quality, defects, sawing method, and kerf. Species identification, grading, and defect assessment should be verified with qualified professionals for commercial transactions.
