Why Lumber Sizes Are Confusing
When you buy a "2x4" from a modern lumber yard, it actually measures 1-1/2" x 3-1/2". This discrepancy exists because modern lumber is surfaced (planed smooth) after it's cut, removing approximately 1/2" from each face.
The "nominal" size (e.g., 2x4) refers to the rough-sawn dimension before planing. The "actual" size is what you actually receive. This convention has been standardized since 1964 by the American Lumber Standard Committee (ALSC). Before that date, sizing practices varied by region and mill, and most lumber was sold at or very close to its nominal dimensions.
The size reduction happens in two stages. First, kiln drying shrinks the wood as moisture leaves the cell walls — typically reducing each dimension by about 1/16" to 1/8". Second, surfacing (planing) removes another 1/8" to 3/16" from each face to create a smooth, uniform surface. The total reduction is approximately 1/2" on each dimension for boards under 2" nominal, and 3/4" on each dimension for larger timbers.
This means a modern 2x4 loses about 25% of its cross-sectional area compared to a true 2" x 4" board. For a single stud, this might not matter much. But across an entire project — a deck, a framing package, a wall of shelving — the cumulative material difference is significant.
Reclaimed lumber, however, was often cut before modern standards. Many pieces are "true" to their nominal size — a reclaimed 2x4 is often a full 2" x 4", giving you more wood per board. This can be a major advantage for restoration projects, structural upgrades, and any application where maximum cross-section matters.
Complete Softwood Dimensional Chart
The following table covers every standard softwood dimensional lumber size from 1x2 through 12x12. The "Actual (Modern)" column shows what you receive from any modern lumber yard. The "Reclaimed (Typical)" column shows the dimensions you can generally expect from our reclaimed inventory.
| Nominal | Actual (Modern) | Reclaimed (Typical) |
|---|---|---|
| 1x2 | 3/4" x 1-1/2" | ~1" x 2" |
| 1x3 | 3/4" x 2-1/2" | ~1" x 3" |
| 1x4 | 3/4" x 3-1/2" | ~1" x 4" |
| 1x6 | 3/4" x 5-1/2" | ~1" x 6" |
| 1x8 | 3/4" x 7-1/4" | ~1" x 8" |
| 1x10 | 3/4" x 9-1/4" | ~1" x 10" |
| 1x12 | 3/4" x 11-1/4" | ~1" x 12" |
| 2x2 | 1-1/2" x 1-1/2" | ~2" x 2" |
| 2x3 | 1-1/2" x 2-1/2" | ~2" x 3" |
| 2x4 | 1-1/2" x 3-1/2" | ~2" x 4" |
| 2x6 | 1-1/2" x 5-1/2" | ~2" x 6" |
| 2x8 | 1-1/2" x 7-1/4" | ~2" x 8" |
| 2x10 | 1-1/2" x 9-1/4" | ~2" x 10" |
| 2x12 | 1-1/2" x 11-1/4" | ~2" x 12" |
| 3x3 | 2-1/2" x 2-1/2" | ~3" x 3" |
| 3x6 | 2-1/2" x 5-1/2" | ~3" x 6" |
| 4x4 | 3-1/2" x 3-1/2" | ~4" x 4" |
| 4x6 | 3-1/2" x 5-1/2" | ~4" x 6" |
| 6x6 | 5-1/2" x 5-1/2" | ~6" x 6" |
| 6x8 | 5-1/2" x 7-1/2" | ~6" x 8" |
| 8x8 | 7-1/4" x 7-1/4" | ~8" x 8" |
| 10x10 | 9-1/4" x 9-1/4" | ~10" x 10" |
| 12x12 | 11-1/4" x 11-1/4" | ~12" x 12" |
Material Advantage: Comparing cross-sectional areas shows the real benefit of reclaimed wood. A modern 2x4 has 5.25 sq in of cross-section; a reclaimed true 2x4 has 8.0 sq in — that is 52% more material with the same nominal name.
Essential Concept
Understanding Board Feet
A board foot (BF) is the standard unit of volume for lumber in the United States and Canada. One board foot equals a piece that is 1 inch thick, 12 inches wide, and 12 inches long — or equivalently, 144 cubic inches of wood.
The formula is straightforward:
If your length is in feet rather than inches, you can use the shortcut:
Board feet are always calculated using nominal dimensions for pricing purposes, even though the actual wood you receive is smaller. This is an industry-wide convention. When ordering reclaimed wood at true dimensions, you may get more physical wood per board foot — an added value that is not reflected in the standard calculation.
Example Calculations
(2 x 4 x 96) / 144 = 5.33 BF
(2 x 6 x 120) / 144 = 10.00 BF
(1 x 12 x 96) / 144 = 8.00 BF
(6 x 6 x 144) / 144 = 36.00 BF
(1 x 8 x 72) / 144 = 4.00 BF
Linear Foot vs. Board Foot vs. Square Foot
These three measurement units are frequently confused, but each serves a distinct purpose. Understanding the differences is essential for accurate ordering, pricing, and project planning.
| Unit | Measures | Formula | Used For | Example |
|---|---|---|---|---|
| Linear Foot (LF) | Length only | 1 LF = 12 inches of length | Trim, molding, studs, poles | 8 ft board = 8 LF |
| Board Foot (BF) | Volume (3D) | T" x W" x L" / 144 | Rough lumber, timber, beams | 2x6x8ft = 8 BF |
| Square Foot (SF) | Area (2D) | W" x L" / 144 | Flooring, siding, panels | 6" wide x 8ft = 4 SF |
Standard Lengths
Modern lumber comes in standard 2-foot increments (8, 10, 12, 14, 16, 20-foot boards). Reclaimed lumber lengths vary — we stock pieces from 4 feet to 30+ feet depending on source.
Longer lengths command a premium in the reclaimed market because they are harder to salvage intact. Boards over 16 feet are especially prized for open-span ceiling work, long benches, continuous stair stringers, and architectural features where visible joints would be undesirable.
| Length (ft) | Inches | Meters | Availability |
|---|---|---|---|
| 4 | 48 | 1.22 | Reclaimed common, modern special order |
| 6 | 72 | 1.83 | Reclaimed common, modern less common |
| 8 | 96 | 2.44 | Most common standard length |
| 10 | 120 | 3.05 | Standard length, widely stocked |
| 12 | 144 | 3.66 | Standard length, widely stocked |
| 14 | 168 | 4.27 | Standard, may require pre-order |
| 16 | 192 | 4.88 | Standard maximum for most species |
| 18 | 216 | 5.49 | Specialty / reclaimed only |
| 20 | 240 | 6.10 | Available in select species and reclaimed |
| 24 | 288 | 7.32 | Reclaimed timbers and select species |
| 30+ | 360+ | 9.14+ | Rare reclaimed — call for availability |
Hardwood vs. Softwood Sizing
Softwood and hardwood use completely different sizing systems. Softwood follows the nominal dimensional system (2x4, 2x6, etc.). Hardwood follows the quarter system based on rough thickness, with random widths and lengths. Understanding both is essential for anyone working with reclaimed wood, since salvaged material frequently includes both types.
Softwood (Pine, Fir, Spruce, Cedar)
- Sized using the nominal system (2x4, 2x6, etc.)
- Actual size is smaller after kiln drying and surfacing
- Available in standard widths and lengths
- Reclaimed softwood is often true to nominal dimensions
- Used primarily for framing, structural, decking, siding, and general construction
- Graded for structural strength (Select, #1, #2, #3, Utility)
- Most common species in reclaimed: heart pine, Douglas fir, white pine, hemlock, spruce
Hardwood (Oak, Maple, Cherry, Walnut)
- Sized by "quarter" thickness: 4/4 (1"), 5/4 (1-1/4"), 6/4 (1-1/2"), 8/4 (2"), etc.
- Width and length are random — you buy what the tree produces
- Rough-sawn thickness is the quoted dimension; surfacing removes 3/16" per face
- Reclaimed hardwood typically arrives in random widths and lengths
- Used for furniture, cabinetry, flooring, trim, and decorative applications
- Graded by percentage of clear, defect-free face (NHLA system)
- Most common species in reclaimed: white oak, red oak, maple, chestnut, elm, walnut
Hardwood Quarter Thickness Reference
Hardwood thickness is described in "quarters" of an inch. The number before the slash tells you how many quarter-inches thick the rough board is. After surfacing (S2S — surfaced two sides), the board loses approximately 3/16" from each face.
| Quarter Designation | Rough Thickness | Surfaced (S2S) | Metric |
|---|---|---|---|
| 3/4 (3/4") | 3/4" | 9/16" | 19.1 mm |
| 4/4 (1") | 1" | 13/16" | 25.4 mm |
| 5/4 (1-1/4") | 1-1/4" | 1-1/16" | 31.8 mm |
| 6/4 (1-1/2") | 1-1/2" | 1-5/16" | 38.1 mm |
| 8/4 (2") | 2" | 1-13/16" | 50.8 mm |
| 10/4 (2-1/2") | 2-1/2" | 2-5/16" | 63.5 mm |
| 12/4 (3") | 3" | 2-13/16" | 76.2 mm |
| 16/4 (4") | 4" | 3-13/16" | 101.6 mm |
International Reference
Imperial to Metric Conversion Table
For international clients, architects working with metric plans, or anyone who needs precise millimeter values, use this conversion reference. All values are exact conversions based on 1 inch = 25.4 mm.
| Imperial (inches) | Millimeters (mm) | Centimeters (cm) |
|---|---|---|
| 1/8" | 3.175 | 0.318 |
| 1/4" | 6.350 | 0.635 |
| 3/8" | 9.525 | 0.953 |
| 1/2" | 12.700 | 1.270 |
| 5/8" | 15.875 | 1.588 |
| 3/4" | 19.050 | 1.905 |
| 7/8" | 22.225 | 2.223 |
| 1" | 25.400 | 2.540 |
| 1-1/2" | 38.100 | 3.810 |
| 2" | 50.800 | 5.080 |
| 3" | 76.200 | 7.620 |
| 3-1/2" | 88.900 | 8.890 |
| 4" | 101.600 | 10.160 |
| 5-1/2" | 139.700 | 13.970 |
| 6" | 152.400 | 15.240 |
| 7-1/4" | 184.150 | 18.415 |
| 8" | 203.200 | 20.320 |
| 9-1/4" | 234.950 | 23.495 |
| 10" | 254.000 | 25.400 |
| 11-1/4" | 285.750 | 28.575 |
| 12" | 304.800 | 30.480 |
Reclaimed Wood Specifics
Tolerance Expectations for Reclaimed Lumber
Because reclaimed wood was often milled with older equipment and has aged over decades or even a century, you should expect slightly different tolerances compared to modern dimensional lumber. Here is what to plan for:
Thickness Tolerance
Expect +/- 1/8" variation in thickness across a batch. Individual boards are generally consistent along their length, but different boards from the same lot may vary slightly. For projects requiring uniform thickness, request re-milling to a specific dimension.
Width Tolerance
Width may vary +/- 1/8" to 1/4" between boards. Wider reclaimed boards (10" and above) may have more variation. If consistent width is critical for your design, specify ripping to a standard width when ordering.
Length Tolerance
Reclaimed boards are typically sold at their salvaged length. Ends may need trimming to remove damage, splitting, or old fastener holes. We recommend ordering boards at least 6 inches longer than your finished need to allow for end trimming.
Squareness
Older saw blades and hand-milling techniques sometimes produced boards that are not perfectly square. Check with a combination square before cutting joinery. If squareness is critical, request S4S (surfaced four sides) processing.
Tips for Measuring Reclaimed Wood
Measure in Three Places
Always measure the width and thickness at both ends and the middle of the board. Reclaimed wood can taper or vary slightly along its length. Use the smallest measurement for planning purposes.
Account for Surface Irregularities
Reclaimed boards may have saw marks, hand-hewn textures, or slight warping on one face. If you plan to leave the surface rough for character, measure the thickest point. If you plan to surface it smooth, subtract 1/8" per face for planing allowance.
Check for Embedded Fasteners Before Measuring
Old nails, screws, and metal fragments can affect your usable dimensions. Run a metal detector or strong magnet along the board before planning precise cuts. A hidden nail can destroy a planer blade and ruin a measurement plan.
Use Calipers for Critical Dimensions
For joinery work, tongue-and-groove fitting, or any application where a 1/32" difference matters, use digital calipers rather than a tape measure. Calipers give you precision to 0.001" — essential for tight-fitting work.
Record Moisture Content with Dimensions
Wood dimensions change with moisture content. Record the MC% alongside your measurements so you can predict how the wood will behave as it acclimates to its final environment. A board at 18% MC will be slightly larger than the same board at 8% MC.
Label and Inventory Each Board
For large reclaimed orders, number each board and record its dimensions on a master list. This makes project planning much easier and helps you match specific boards to specific locations in your design.