What is lumber yield?

Lumber yield is the percentage of usable, defect-free wood you get from rough stock. Starting with 100 board feet of rough lumber, you might end up with 50–70 board feet of usable material after removing defects, planing, and cutting.

What do lumber grades mean?

FAS (First and Seconds) is the highest grade with fewest defects, yielding about 83% clear wood. Select is next at about 75%. No. 1 Common yields about 67%, and No. 2 Common about 50%. Lower grades cost less but produce more waste.

How much does planing remove?

Planing typically reduces board footage by 10–15%. A 25mm (1-inch) rough board planed to 20mm loses 20% of its thickness. Width losses from edge jointing add another 5–10%. The calculator default of 15% covers both.

How should I account for yield when buying timber?

Divide the board feet you need by the expected yield. If you need 50 BF of usable oak and expect 65% yield, buy 50 ÷ 0.65 = 77 BF of rough stock. Always round up and add a small buffer.

WoodCalcs

Lumber Yield Calculator — Usable Wood from Rough Stock

Calculate how much usable lumber you get from rough stock after accounting for defects, planing, and cutting waste.

Rough Stock

Total rough lumber in board feet

Lumber Grade

Planing Loss

Lost to thicknessing and jointing

Kerf / Cutting Loss

Lost to saw cuts

How We Calculate This

This calculator estimates usable lumber by applying three successive waste factors to rough stock.

Step 1: Grade yield

Removes defective areas (knots, splits, sapwood) based on the lumber grade.

Step 2: Planing loss

Accounts for material removed during thicknessing and edge jointing (default 15%).

Step 3: Kerf loss

Accounts for material lost to saw cuts when breaking boards into project parts (default 5%).

Overall yield

The final usable lumber is the result after all three factors. Typical overall yield ranges from 35% (low-grade timber) to 70% (high-grade FAS).

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.