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Lumber recovery and overrun

See how much of the log becomes lumber, slabs, edgings and sawdust, what the log costs per MBF of lumber, the overrun on your log scale and what each point of recovery is worth.

Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.

Preliminary estimate
Logs sawn per month
Lumber produced per month
See what was read

The list always uses nominal inches and feet; board feet = thickness × width × length ÷ 12.

Saw and residues
Prices and costs
Target
Economic analysis
—Lumber recovery
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Where the log goes

Monthly log volume split into lumber, slabs and edgings, sawdust and bark.

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Monthly margin versus recovery

Lumber and residue revenue minus logs and sawing cost, for recoveries from 30% to 65%.

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Output by item

Next step

Take this page’s results to another calculator with the fields already filled in.

Project payback

Cash flow of the improvement: investment in year 0 and annual savings escalated at the rate entered, discounted at the MARR.

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The calculation report gathers this page's inputs, results, equations, assumptions and references, with fields for project, engineer and revision. The full report also includes the charts and interpretations, in color. In the print dialog, choose Save as PDF.

Method, assumptions and references

Equations used

Cubic recovery = V_lumber ÷ V_logs inside bark; tally (bf) = Σ thickness (in) × width (in) × length (ft) ÷ 12 × pieces
Logs = V_logs ÷ (π · D² ÷ 4 · L); sawdust = logs × cuts × kerf × (π ÷ 4 · D) × L; LRF = tally ÷ log ft³; overrun = tally ÷ log scale − 1
Slabs and edgings = V_logs inside bark − V_lumber − sawdust; weight = volume × green density
Margin = lumber price × tally + residue value − log cost − sawing cost × V_logs
Annual gain at target = (target × V_logs − V_lumber) × (lumber price − residue value per unit volume) × months

Assumptions and limits

  • Sawdust assumes cuts through the full log length with an average cut face of π/4 of the diameter; the rest is treated as slabs, edgings and trim ends. Drying shrinkage and green oversizing are not separated. The tally uses nominal sizes, as lumber is sold.
  • Sawing cost per unit of log covers labor, power, saws and maintenance; taxes, freight and kiln drying are excluded. Residues are valued by green weight; bark is not valued.
  • The annual gain assumes all extra lumber at the target sells at the same price and that log input stays the same.

Standards and technical documents

  • Vital, B. R. Planejamento e operação de serrarias. Viçosa: Editora UFV, 2008
  • Steele, P. H. Factors determining lumber recovery in sawmilling. USDA Forest Products Laboratory, General Technical Report FPL-39, 1984
  • Williston, E. M. Lumber Manufacturing: The Design and Operation of Sawmills and Planer Mills. Miller Freeman, 1988
  • USDA Forest Service. National Forest Log Scaling Handbook, FSH 2409.11

U.S. regulations

  • OSHA 29 CFR 1910.265: Sawmills
  • OSHA 29 CFR 1910.213: Woodworking machinery requirements
  • Lacey Act (16 U.S.C. 3371–3378): legal origin of timber

Frequently asked questions

What is lumber recovery?

It is how much lumber you get from your logs. In cubic terms it is lumber volume over log volume inside bark; US mills also use the lumber recovery factor (LRF, board feet per cubic foot of log) and overrun, the lumber tally above the log scale. In the example, 5,000 ft³ of logs scaled at 25,000 bf produced 30,000 bf: LRF 6.0 and overrun 20%.

What is a normal overrun?

It depends on the log rule. On Doyle, small logs often show 20% to 50% overrun or more, because Doyle underestimates them; on Scribner it is lower, and on International 1/4-inch it is close to zero. Compare overrun only on the same rule and log size.

How is sawdust estimated?

From the number of logs (volume ÷ volume of the average log), cuts per log and kerf: each cut makes a slab of sawdust as wide as the kerf and about 0.79 times the diameter tall. In the example, with a 1/8 in kerf and 10 cuts per log, sawdust is about 520 ft³ a month, 10% of the log volume.

Where do I get the inputs?

Log volume and scale come from the scale tickets or the log scale calculator; the lumber tally from your production report; kerf from measuring the cut on a board; prices from your lumber and residue sales.

How do I read the example result?

At $250 per MBF of log scale, logs cost $6,250 a month, about $208 per MBF of lumber. Lumber at $500/MBF plus about $1,080 of residues brings about $16,080, and the margin after logs and sawing cost is about $3,830 a month. Each point of cubic recovery is worth about $280 a month at these prices.

What are the limits?

Sawdust is a geometric estimate; the rest is lumped as slabs and edgings, without separating drying shrinkage, oversizing and trim. Taxes, freight, kiln drying and financing are excluded. Confirm recovery with a marked-log sawing study before investing.

How can a mill improve recovery?

Sort logs by diameter, use sawing patterns for each class, keep saws sharp and aligned, cut kerf and green oversizing, and recover short lumber from slabs. Use the target and investment fields to see how fast an upgrade pays back.