Timber Volume Calculator
Enter timber dimensions and quantity to get board feet, cubic feet, MBF, and estimated dry weight. Works for rectangular structural timber, large-section lumber, and round logs using the Doyle log rule.
Pricing a timber order or quoting a sawmill? Enter your dimensions — get board feet, cubic feet, MBF, and weight in one calculation.
Rectangular for beams, posts, and dimensional lumber · Round for logs using the Doyle rule
Nominal width — e.g. enter 6 for a 6×8, even though actual is 5.5″
Enter 8 for a 6×8 · Enter 6 for a 6×6 post · Enter 12 for a 6×12 beam
Enter length in feet · For 16-ft members enter 16, not 192
Number of pieces at this size in the order
Dry weight at ~12% moisture content · Green lumber weighs 20–50% more
PT 6×6 ~$1.75/LF — convert: $/LF ÷ BF/LF = $/BF · Hardwood timber: $4–$15+/BF
Enter timber dimensions
to calculate volume
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Board feet vs cubic feet
Board feet and cubic feet both measure lumber volume, but they answer different questions. Board feet use nominal dimensions and are the pricing and purchasing unit for the lumber industry. Cubic feet use actual dimensions and are needed for weight calculations, shipping logistics, and any context where the true volume of wood matters.
Volume Formulas
BF = (W″ × H″ × L') ÷ 12 [nominal dimensions]
CF = (W″ × H″ × L') ÷ 144 [actual dimensions]
CF × 12 = BF [nominal conversion only]
The relationship between BF and CF is exact only when using the same dimensions. When calculating BF for a 6×8 timber, you use the nominal 6″ × 8″ = 48 sq in. When calculating CF for actual weight, you use the actual 5.5″ × 7.5″ = 41.25 sq in. The difference is about 14% — which means weight estimates based on board feet are approximately 14% too high for a 6×8 compared to weight estimates based on actual cubic feet. For accurate weight estimates, always use actual dimensions in the cubic foot formula. This calculator handles both. For the board foot calculation on standard-dimension framing lumber with worked examples on hardwood purchasing and sawmill ordering, see the board feet guide. For the focused board foot calculator on standard sizes, the board foot calculator is the targeted tool.
Board feet per piece — timber sizes
Large-section timber carries significantly more board feet per linear foot than standard framing lumber. A single 16-foot 6×12 beam contains 96 BF — more than the combined board feet of six 16-foot 2×6 framing joists. Timber framing projects are priced and quoted in MBF precisely because individual member volumes are large enough to make per-piece pricing impractical.
| Nominal size | BF per LF | 8 ft piece (BF) | 16 ft piece (BF) | Dry weight per LF (SYP) |
|---|---|---|---|---|
| 4×4 | 1.33 | 10.7 | 21.3 | 4.4 lb |
| 4×6 | 2.00 | 16.0 | 32.0 | 6.5 lb |
| 6×6 | 3.00 | 24.0 | 48.0 | 9.8 lb |
| 6×8 | 4.00 | 32.0 | 64.0 | 13.1 lb |
| 6×12 | 6.00 | 48.0 | 96.0 | 19.7 lb |
| 8×8 | 5.33 | 42.7 | 85.3 | 17.5 lb |
| 8×12 | 8.00 | 64.0 | 128.0 | 26.2 lb |
| 10×12 | 10.00 | 80.0 | 160.0 | 32.8 lb |
A 16-foot 8×12 timber weighs approximately 420 lbs dry — and closer to 600 lbs green. Timber framing crews require lifting equipment or robust rigging for any section over 200 lbs. When planning a timber frame delivery, weight is the primary logistics constraint, not piece count. For sizing the structural members in a timber frame, the beam size calculator determines the minimum structural dimension for any span and load.
Weight by species
Wood density varies significantly across species. The figures below are for kiln-dried lumber at approximately 12% moisture content — the stable condition of lumber that has reached equilibrium with indoor environments. Green (freshly milled) timber carries 30–100% more water by weight depending on species and will be substantially heavier.
| Species | Dry density (lb/CF) | Green density (lb/CF, approx) | Notes |
|---|---|---|---|
| Southern Yellow Pine (SYP) | 37 | 55–60 | Common PT lumber |
| Douglas Fir-Larch | 34 | 45–55 | Pacific Northwest framing |
| SPF (Spruce-Pine-Fir) | 29 | 38–48 | Canadian framing lumber |
| Hem-Fir | 28 | 38–45 | Coastal species |
| White Oak | 47 | 62–75 | Heaviest common domestic |
| Hard Maple | 44 | 58–70 | Flooring, butcher blocks |
| Western Red Cedar | 23 | 28–35 | Lightest structural wood |
Pressure treatment adds 2–4 lbs per cubic foot to the dry weight as chemical preservative is retained in the wood. A cubic foot of dry SYP at 37 lb/CF becomes approximately 39–41 lb/CF after ACQ treatment. For delivery weight calculations, use the treated weight. For dead load calculations in structural engineering, use the dry weight — the chemical weight is negligible in structural load calculations and is not included in published dead load tables.
Log rules — Doyle and Scribner
A log rule converts round log dimensions into the estimated board feet of sawn lumber the log will yield. The Doyle rule is the most common for private timber sales in the eastern US. The Scribner rule is more accurate and is used for US Forest Service timber sales and most western markets.
Doyle rule: BF = ((D − 4) ÷ 4)² × L. For a 16-inch log at 12 feet: ((16−4)/4)² × 12 = 9 × 12 = 108 BF. The Doyle rule significantly underestimates yield for small logs (under 12 inches) — a 6-inch log yields only 3 BF per foot by Doyle, but may actually produce more at the saw. For logs under 12 inches, negotiate based on cubic feet rather than Doyle board feet.
Scribner rule: Uses empirical tables rather than a formula. Generally yields 10–20% more board feet than Doyle for the same log, particularly for smaller diameters. Ask your sawmill which rule they use before calculating your order.
MBF pricing reference
Sawmills and wholesale timber distributors quote in MBF (thousand board feet). The table below converts common order volumes to give context for pricing conversations with timber suppliers.
| Application | Typical volume | MBF equivalent |
|---|---|---|
| Small cabin timber frame (400 SF) | 800–1,500 BF | 0.8–1.5 MBF |
| Medium timber frame (1,200 SF) | 2,000–4,000 BF | 2.0–4.0 MBF |
| Deck framing package (400 SF deck) | 300–600 BF | 0.3–0.6 MBF |
| Floor joist package (1,000 SF) | 800–1,200 BF | 0.8–1.2 MBF |
| Wall framing package (2,000 SF house) | 8,000–12,000 BF | 8.0–12.0 MBF |
For a deck framing package with specific beam sizes, the lumber cost calculator handles the per-piece pricing once you have the BF total from this calculator. For the structural sizing of those beams, use the beam size calculator before calculating volume — it is more cost-effective to confirm the structural specification before ordering material.
Frequently asked questions
What is the difference between board feet and cubic feet for timber?
Board feet use nominal dimensions and are the pricing unit for lumber. Cubic feet use actual dimensions and are needed for accurate weight calculations and shipping. One board foot equals 144 cubic inches. The conversion BF × 0.0833 = CF only holds when using the same dimensions in both calculations. For actual weight, use cubic feet with actual dimensions — nominal BF overestimates cubic volume by 10–20% for most timber sizes.
How do I calculate board feet for a 6x6 post?
BF = (6 × 6 × length_ft) ÷ 12. For a 10-foot 6×6: (6 × 6 × 10) ÷ 12 = 30 BF per post. At 20 posts, that is 600 BF total. At a sawmill quoting $0.90 per BF (example), the post stock costs $540. For retail PT 6×6 priced at $1.75/LF, the same 20 posts at 10 feet each cost $350 — the per-BF equivalent is approximately $0.58/BF.
How much does structural timber weigh per cubic foot?
Dry weight at 12% moisture content: SYP 37 lb/CF, Douglas Fir 34 lb/CF, SPF 29 lb/CF, Hem-Fir 28 lb/CF, Western Red Cedar 23 lb/CF, White Oak 47 lb/CF. Green lumber weighs 20 to 50% more. Pressure-treated lumber adds 2 to 4 lb/CF. Use this calculator's species selector to get weight estimates for your specific timber order.
What is MBF and how does it relate to cubic feet?
MBF is thousand board feet — the standard unit for wholesale lumber pricing. One MBF equals 1,000 BF, or approximately 83.3 cubic feet based on the nominal conversion. Sawmills and large distributors quote in MBF because individual member volumes are large enough to make per-piece pricing impractical. To convert your order to MBF, divide total board feet by 1,000.
How do I calculate timber volume for a round log?
For gross cubic volume: CF = π × (radius_in ÷ 12)² × length_ft. For board feet using the Doyle rule: BF = ((diameter − 4) ÷ 4)² × length_ft. For a 12-inch diameter, 16-foot log: BF = ((12−4)/4)² × 16 = 256 BF. The Doyle rule underestimates yield for logs under 12 inches diameter — use cubic feet for small-diameter logs when negotiating with a sawmill.
What is the Doyle log rule and when is it used?
The Doyle rule is the most widely used log volume formula in the eastern United States: BF = ((diameter − 4) / 4)² × length. It is simple to calculate in the field but underestimates yield on small logs and overestimates on very large logs. Despite these inaccuracies, it remains the standard for private timber sales in most eastern states. The Scribner rule is more accurate and is used for government timber sales and many western markets.
How many board feet are in a standard timber framing package?
A small post-and-beam cabin (400 to 600 SF) typically uses 800 to 1,500 BF of timber stock. A medium timber frame (1,200 SF) may use 2,000 to 4,000 BF. Large commercial frames are quoted in MBF. Use this calculator to tally BF for each unique timber size in your cut list and sum for the total order volume before requesting a sawmill quote.
References
Forest Products Laboratory. (2021). Wood Handbook: Wood as an Engineering Material. USDA Forest Service. fpl.fs.usda.gov
National Hardwood Lumber Association. (2023). Rules for the Measurement and Inspection of Hardwood and Cypress. NHLA.
Western Wood Products Association. (2024). Western Lumber Product Use Manual. WWPA. wwpa.org
Hood Distribution. (2026). Product Weights — Lumber Reference. hooddistribution.com