Lumber volume · multiple sizes · cost per board foot
Board Foot Calculator
Calculate lumber board feet from thickness, width, length, and quantity. Combine different sizes and imperial or metric rows, then see entered volume, an optional extra allowance, and quoted lumber cost.
Worked example
- Board feet per piece
- 8 BF
- With an optional 10% extra
- 88 BF
- A volume unit
- Not linear feet
Illustrative example. Measurements, allowances, product details, and prices are not prefilled from this example.
Your lumber estimate
Measure volume, then plan purchasing
One board foot is 144 cubic inches: a board 1 in thick × 12 in wide × 1 ft long. Add one or more sizes to see the total and an optional budget.
Suggest an improvement
Choose and measure
Board-foot abbreviations and quarter-thickness labels
BF and BDFT both abbreviate board feet. One board foot is 144 cubic inches of lumber. In quarter-thickness notation, 4/4 denotes a nominal 1 in thickness and 8/4 denotes 2 in. These labels do not guarantee the final dressed thickness.
Enter a numeric thickness in the selected unit, such as 1 or 2 inches, using the dimensions required by your supplier’s tally or quote. Do not type 4/4 into a thickness field. The calculator does not automatically apply lumber grading, surfacing, or commercial tally rules.
Only need the length of trim or boards? The Linear Foot Calculator adds lengths without thickness or width. For a decorative wall’s spacing and vertical trim, use the Board and Batten Calculator.
Measure first
Match the dimensions used by your lumber supplier.
Enter each lumber size on a separate row. Imperial rows use thickness and width in inches and length in feet; metric rows use millimeters and meters. Choose the dimensions used for your supplier’s tally or quote. The calculator does not automatically replace nominal dimensions with dressed sizes.
One board foot
One board foot is 144 cubic inches: 1 in thick × 12 in wide × 12 in long. It is a volume, not an area or a length.
Imperial lumber
Board feet = thickness (in) × width (in) × length (ft) × quantity ÷ 12. Add the result for each row.
Metric lumber
Convert millimeters to inches and meters to feet using exact unit factors, then use the same volume formula. Mixed-unit rows are totaled together.
Allowance and cost
Planning volume = entered volume × (1 + allowance). The quoted price per board foot is applied separately to entered volume and planning volume; the allowance does not change the dimensions you entered.
From measurement to purchase
Ten 2 × 6 in pieces, each 8 ft long, total 2 × 6 × 8 × 10 ÷ 12 = 80 BF. If you add 10% for planning, the total becomes 88 BF. At an illustrative $5/BF, entered-volume cost is $400 and allowance-based planning cost is $440. These are geometric totals from the entered dimensions, not an assertion about a seller’s grading or tally rounding.
FAQ
Board Foot planning questions
Is a board foot the same as a linear foot?
No. Board feet measure volume and depend on thickness and width. Linear feet measure length alone. Two pieces of the same length can have different board-foot quantities.
Should I use nominal or actual lumber size?
Use the dimensions that match your intended measurement or supplier billing method. Rough lumber tally and dressed physical dimensions may differ. No nominal-to-actual table or industry grading rule is silently applied.
Can I enter several sizes?
Yes. Add one row per thickness, width and length combination, with its own quantity. Each row can use imperial or metric dimensions; switching units converts entered dimensions.
Does this estimate logs or a tree?
No. It estimates rectangular lumber from entered dimensions. Log rules, sawmill recovery, bark and live-edge geometry are different tasks.
References
Check product specifications before ordering.
Wood-Mizer: What is a Board Foot?
Sawmill manufacturer explanation of board-foot formulas and tally examples.
View reference ↗Woodworkers Source: lumber thickness and measurement FAQ
Supplier guidance on quarter-thickness labels and its own board-foot tally method; confirm your supplier’s billing dimensions.
View reference ↗