MATERIALFOREMAN · SHEET L-001 · FRAMING & STRUCTURE
CALC-001 · DRAWING NO. L-001 · REV A

Lumber calculator.

Drafted to scale · cited sources · honest numbers

Select a nominal size, enter board length and quantity. The calculator returns board feet using nominal dimensions (industry pricing convention), actual dimensions for coverage, and a material-cost range.

◈ DRAFTING PANEL · LUMBER TAKEOFF · N.T.S. SHEET L-001 · REV A
Redline · scope notice Board-foot quantity only. Does not calculate structural loads, spans, or joist spacing. Consult AWC NDS span tables for structural sizing. Board feet use nominal dimensions per lumber industry convention.
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Note 01 · Field Procedure

How to order lumber

  1. Identify the nominal size you need. A '2x4' is 1.5 x 3.5 in. actual. Nominal dimensions are used for pricing; actual dimensions determine fit in the wall or deck frame.
  2. Measure the length you need in feet. Standard stock lengths run 8, 10, 12, 14, and 16 ft. Anything over 16 ft is special-order at most yards.
  3. Count how many boards. The calculator multiplies board feet per piece by your quantity and applies a waste factor based on use (framing 5%, decking 10%, trim 15%).
  4. If the lumber contacts ground or stays wet, specify pressure-treated. AWPA U1 defines use categories: UC4A for ground contact, UC3B for above-grade exterior framing.
Note 02 · Equation

The formula

BF  =  (T × W × L) ÷ 12
Tnominal thickness in inches
Wnominal width in inches
Lboard length in feet
Board feet use nominal dimensions for pricing. Actual face dimensions are smaller per PS 20.
Note 03 · Sanity Ranges

Lumber by project size

T Use case Notes
10-50 bfSmall project / shelvingA few boards. Buy at the yard; no delivery needed.
100-200 bfDeck frame / small additionBudget for delivery. Check straight-edge quality on long boards.
500-1,000 bfRoom addition / garagePallet pricing usually kicks in. Coordinate delivery with framing schedule.
3,000+ bfWhole-house frameNegotiate mill-direct or bulk pricing. Factor in crane/boom truck for second-floor delivery.
Note 04 · References

Sources

Authorities cited on this sheet
  1. AWC National Design Specification (NDS) · Structural design reference for wood construction. Span tables, fastener schedules, and load calculations. This calculator does not perform structural analysis.
  2. AWPA U1: Use Category System for Treated Wood · Defines pressure-treatment use categories. UC3B for above-grade exterior, UC4A for ground contact, UC4B for ground contact heavy duty.
  3. American Lumber Standard Committee (ALSC) PS 20 · Voluntary product standard for softwood lumber. Defines nominal-to-actual size conversions. A '2x4' is 1.5 x 3.5 in. actual.
Note 05 · Field Manual

What the sheet count does not tell you

Twelve joists, worked out

Take a deck frame: twelve 2x10 joists, 12 feet each. Board feet use nominal dimensions by lumber-industry convention, so a 2x10 is figured at 2 by 10 even though it actually measures 1.5 by 9.25. The math is nominal thickness times nominal width times length in feet, divided by 12: 2 times 10 times 12 over 12 is 20 board feet per joist. Twelve joists is 240 board feet, and the 5 percent framing waste brings it to 252. At national-baseline pricing that is roughly 200 dollars in SPF framing lumber and over 1,200 for the same volume in cedar or the longer pressure-treated sections. The actual 9.25 inch face is what matters for fit; the nominal 2 by 10 is what the yard prices.

Nominal versus actual

Lumber is sold by a name bigger than the wood. A 2x4 measures 1.5 by 3.5 inches; a 2x10 is 1.5 by 9.25; a 1x6 is 0.75 by 5.5. The nominal size is the rough-sawn green dimension before the mill dries and planes it smooth, and it survives as the pricing and ordering label under American Lumber Standard PS 20. Two practical consequences follow. Board feet are figured on the nominal size, which is why this calculator prices on nominal. And fit is governed by the actual size, which is why three 2x4 studs stacked in a corner measure 4.5 inches, not 6, and why a 2x10 joist is 9.25 inches deep when you size the rim board. Use nominal to buy, actual to build.

Treatment, length, and grade

Three things change the order beyond board feet. Pressure treatment is required anywhere the wood touches ground or stays wet: AWPA U1 use category UC4A for ground contact, UC3B for above-grade exterior framing. Treated lumber costs roughly 40 percent more than the equivalent SPF and ships heavier and wetter, so it moves as it dries. Length is the second: stock runs 8, 10, 12, 14, and 16 feet, and anything over 16 is special-order at most yards, with longer lead time and a premium. Grade is the third. Structural framing needs at least #2 grade; bargain economy and utility grades carry knots and wane that disqualify them from load paths. This calculator counts board feet; it does not size a beam or a joist span. Get that from the AWC span tables or an engineer, then come back for the quantity.

Note 06 · Common Questions

Common questions

How do you calculate board feet?
Board feet are nominal thickness times nominal width in inches times length in feet, divided by 12. A 2x4 that is 8 feet long is 2 times 4 times 8 over 12, or 5.33 board feet. A single 2x10 at 12 feet is 20 board feet. Lumber is priced by the board foot on the nominal size, not the actual planed dimension.
What are the actual dimensions of a 2x4?
A 2x4 actually measures 1.5 by 3.5 inches. The 2 by 4 is the nominal name from the rough green size before the mill dries and planes it, kept as the pricing label under PS 20. Others: 2x6 is 1.5 by 5.5, 2x10 is 1.5 by 9.25, 4x4 is 3.5 by 3.5, and 1x6 is 0.75 by 5.5.
How much more does pressure-treated lumber cost?
Pressure-treated runs roughly 40 percent more than the equivalent SPF framing lumber. National-baseline lumber spans about 0.80 dollars per board foot for SPF studs up to around 5 dollars for cedar and the longer treated sections. Specialty hardwoods like oak and ipe run 8 to 20 dollars a board foot and are out of scope here.
Do I need pressure-treated lumber?
Yes anywhere the wood contacts ground or stays wet: deck posts, ledgers, sill plates on concrete, and exterior framing near grade. AWPA U1 calls these UC4A for ground contact and UC3B for above-grade exterior. Interior framing in a dry wall cavity does not need it. When in doubt outdoors, treat it; the cost difference is small against a rotted post.
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SHT L-001 / 014
REV A · 2026-06-07
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