Dimensional Lumber Sizing
Complete reference tables for all common board sizes, with nominal, actual dry, actual green dimensions, and weight per linear foot.
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Understanding Dimensional Lumber Sizes
Dimensional lumber refers to boards with standardized widths and thicknesses. These are the workhorses of construction — framing, sheathing, decking, shelving, and general-purpose woodwork. The tables below show all three key measurements: the nominal name you order by, the actual size after kiln drying and surfacing, and the green (unseasoned) dimension.
Nominal Size
The name used when ordering — based on the rough-sawn dimension before any processing. A "2x4" refers to the pre-dried, pre-planed measurement.
Actual Dry
The real dimension after kiln drying to 19% moisture content or less and surfacing (planing) on all four sides. This is what you actually get at the lumber yard.
Actual Green
The dimension of surfaced lumber with moisture content above 19%. Green lumber is slightly larger because it has not fully shrunk. It will shrink as it dries to equilibrium.
1x Boards (One-By)
| Nominal | Actual (Dry) | Actual (Green) | Weight / LF | BF / LF |
|---|---|---|---|---|
| 1 x 2 | 3/4" x 1-1/2" | 25/32" x 1-9/16" | 0.29 lbs | 0.167 |
| 1 x 3 | 3/4" x 2-1/2" | 25/32" x 2-9/16" | 0.47 lbs | 0.250 |
| 1 x 4 | 3/4" x 3-1/2" | 25/32" x 3-9/16" | 0.64 lbs | 0.333 |
| 1 x 6 | 3/4" x 5-1/2" | 25/32" x 5-5/8" | 1.00 lbs | 0.500 |
| 1 x 8 | 3/4" x 7-1/4" | 25/32" x 7-1/2" | 1.32 lbs | 0.667 |
| 1 x 10 | 3/4" x 9-1/4" | 25/32" x 9-1/2" | 1.69 lbs | 0.833 |
| 1 x 12 | 3/4" x 11-1/4" | 25/32" x 11-1/2" | 2.05 lbs | 1.000 |
2x Boards (Two-By)
| Nominal | Actual (Dry) | Actual (Green) | Weight / LF | BF / LF |
|---|---|---|---|---|
| 2 x 2 | 1-1/2" x 1-1/2" | 1-9/16" x 1-9/16" | 0.54 lbs | 0.333 |
| 2 x 3 | 1-1/2" x 2-1/2" | 1-9/16" x 2-9/16" | 0.90 lbs | 0.500 |
| 2 x 4 | 1-1/2" x 3-1/2" | 1-9/16" x 3-9/16" | 1.28 lbs | 0.667 |
| 2 x 6 | 1-1/2" x 5-1/2" | 1-9/16" x 5-5/8" | 2.00 lbs | 1.000 |
| 2 x 8 | 1-1/2" x 7-1/4" | 1-9/16" x 7-1/2" | 2.64 lbs | 1.333 |
| 2 x 10 | 1-1/2" x 9-1/4" | 1-9/16" x 9-1/2" | 3.37 lbs | 1.667 |
| 2 x 12 | 1-1/2" x 11-1/4" | 1-9/16" x 11-1/2" | 4.10 lbs | 2.000 |
Weight Reference Notes
Species Variation
Weights listed above are approximate for kiln-dried softwood (SPF — Spruce, Pine, Fir) at roughly 35 lbs/ft3. Heavier species like Southern Yellow Pine weigh approximately 20-25% more. Douglas Fir weighs approximately 10-15% more. Lightweight species like Western Red Cedar weigh approximately 20% less.
Moisture Content Impact
Green lumber can weigh 50-100% more than kiln-dried lumber of the same species. A green 2x6 that weighs 2.0 lbs/ft when dry may weigh 3.5 to 4.0 lbs/ft when freshly cut. Air-dried lumber (typically 15-20% MC) falls somewhere in between.
Common Softwood Densities (Kiln Dried)
| Species | Density (lbs/ft3) | Relative Weight |
|---|---|---|
| Western Red Cedar | 23 | Light |
| White Pine | 25 | Light |
| SPF (Spruce/Pine/Fir) | 35 | Standard |
| Douglas Fir | 34 | Medium |
| Hem-Fir | 29 | Medium-Light |
| Southern Yellow Pine | 36 | Heavy |
| White Oak (hardwood) | 47 | Very Heavy |
| Red Oak (hardwood) | 44 | Very Heavy |
Reclaimed Lumber: True Dimension
One of the most significant differences between modern and reclaimed lumber is sizing. Lumber milled before 1964 — and especially before 1900 — was often sold at or very near its nominal dimension. This means a reclaimed "2x4" may actually measure a full 2" x 4", giving you substantially more material than a modern board of the same name.
This matters for several reasons: you get more structural strength, more surface area for finishing, and more wood overall. However, it also means reclaimed boards may not fit perfectly into jigs, fixtures, or framing designed for modern nominal lumber. Always verify actual measurements before mixing reclaimed and modern stock.
| Nominal Size | Modern Actual | Typical Reclaimed | Extra Material |
|---|---|---|---|
| 1 x 4 | 3/4" x 3-1/2" | 7/8" - 1" x 3-3/4" - 4" | Up to 33% more |
| 1 x 6 | 3/4" x 5-1/2" | 7/8" - 1" x 5-3/4" - 6" | Up to 27% more |
| 1 x 8 | 3/4" x 7-1/4" | 7/8" - 1" x 7-1/2" - 8" | Up to 25% more |
| 1 x 12 | 3/4" x 11-1/4" | 7/8" - 1" x 11-1/2" - 12" | Up to 22% more |
| 2 x 4 | 1-1/2" x 3-1/2" | 1-3/4" - 2" x 3-3/4" - 4" | Up to 52% more |
| 2 x 6 | 1-1/2" x 5-1/2" | 1-3/4" - 2" x 5-3/4" - 6" | Up to 45% more |
| 2 x 8 | 1-1/2" x 7-1/4" | 1-3/4" - 2" x 7-1/2" - 8" | Up to 40% more |
| 2 x 10 | 1-1/2" x 9-1/4" | 1-3/4" - 2" x 9-1/2" - 10" | Up to 38% more |
| 2 x 12 | 1-1/2" x 11-1/4" | 1-3/4" - 2" x 11-1/2" - 12" | Up to 35% more |
Important Note on Reclaimed Sizing
Reclaimed lumber dimensions can vary even within a single batch. Boards from the same structure may differ by 1/8" to 1/4" depending on the original sawmill's equipment and practices. We measure and sort all reclaimed stock, and we are happy to pull boards matching your specific dimensional needs. Always communicate your tolerance requirements when ordering.
Tolerances in Reclaimed Lumber
If you have ever ordered reclaimed lumber and noticed that boards within the same batch are not perfectly identical, that is completely normal. Understanding why dimensions vary will help you plan better and avoid surprises on the jobsite.
Why Dimensions Vary
Before modern computerized sawmills existed, lumber was cut by hand-fed circular or band saws. The operator controlled feed speed by hand, and blade deflection under load was common. A board cut at 8 AM when the blade was sharp might measure 1/16" thicker than one cut at 3 PM after hours of use. These small variations compounded across a full day of milling.
Additionally, lumber standards were not nationally unified until 1924 (with the American Lumber Standards) and not standardized to modern nominal rules until 1964. Before those dates, each mill operated to its own specifications. A "2x4" from a sawmill in Iowa might differ from one in Oregon by a quarter inch or more.
Finally, decades of service in a structure introduce additional variation. Compression under load, exposure to moisture cycles, and surface wear all subtly reshape lumber over time. A floor joist that has carried weight for 80 years may be slightly thinner at its center span than at the bearing points.
Typical Tolerance Ranges
When you order reclaimed dimensional lumber from us, here are the realistic tolerance ranges you should expect:
Thickness (1x stock): +/- 1/8"
May measure 3/4" to 1" depending on era
Thickness (2x stock): +/- 3/16"
True dimension stock runs 1-3/4" to full 2"
Width (all stock): +/- 1/4"
Widths can taper along the board length
Length: Exact to +1"
We always cut to at least the length ordered
Squareness: +/- 1/16" per face
Original saw marks may cause slight out-of-square
Straightness (bow): Up to 1/4" per 8 ft
Some bow is inherent in older lumber
What we do to minimize variation: Every board in our inventory is measured, sorted, and binned by actual dimension — not just nominal size. When you place an order, we pull from bins that match your target thickness and width as closely as possible. If you need tighter tolerances, we can re-mill reclaimed stock to exact specifications for an additional processing fee.
Moisture Content & Dimension Changes
Wood is hygroscopic — it absorbs and releases moisture in response to its environment. As moisture content changes, dimensions change with it. Understanding shrinkage rates is essential when working with any lumber, but especially reclaimed stock that may arrive at a different moisture content than your project site's equilibrium.
| Species | Tangential Shrinkage (%) | Radial Shrinkage (%) | Volumetric Shrinkage (%) |
|---|---|---|---|
| White Oak | 10.5 | 5.6 | 16.3 |
| Red Oak | 8.6 | 4.0 | 13.7 |
| Heart Pine | 7.7 | 4.8 | 12.2 |
| Douglas Fir | 7.6 | 4.8 | 11.8 |
| Hard Maple | 9.9 | 4.8 | 14.7 |
| American Chestnut | 6.7 | 3.4 | 11.6 |
| Eastern White Pine | 6.1 | 2.1 | 8.2 |
| Elm | 9.5 | 4.2 | 14.6 |
Shrinkage values represent the total dimensional change from green (fiber saturation point, approximately 28% MC) to oven-dry (0% MC). Source: USDA Forest Products Laboratory Wood Handbook, FPL-GTR-190.
What This Means in Practice
Most reclaimed lumber we ship has been kiln-dried to 8-12% moisture content. If your project site is climate-controlled, the wood will reach equilibrium near 6-9% MC. That small change — just a few percentage points — can still cause measurable dimensional shifts.
For example, a 6" wide flat-sawn Red Oak board dropping from 12% to 7% MC will shrink approximately 1/16" to 3/32" in width. For a single board that is negligible, but across a 20-foot-wide floor with 40 boards, those small gaps add up to roughly 2-1/2" to 3-3/4" of total accumulated gap space if the boards were installed tight with no expansion allowance.
Acclimation Best Practices
Always acclimate reclaimed lumber to the job site before installation. Stack the boards with stickers (spacer strips) between each layer to allow air circulation on all faces.
- Flooring: 5-7 days of acclimation minimum
- Wall paneling: 3-5 days minimum
- Exterior siding: 3-5 days in covered, ventilated area
- Structural timbers: 7-14 days for large cross-sections
Use a pin-type moisture meter to verify that the lumber has reached equilibrium with the site conditions before beginning installation. The target is within 2% of the expected in-service moisture content.
How to Specify Dimensions When Ordering
Clear communication prevents costly mistakes. When you submit an order or quote request for reclaimed dimensional lumber, include the following information for each line item.
State Whether Dimensions Are Nominal or Actual
This is the single most important detail. A "2x6" could mean a modern 1-1/2" x 5-1/2" board or a true 2" x 6" piece. If you need a specific actual dimension, state it explicitly — for example, "Need actual 1-1/2 inches thick by 5-1/2 inches wide." If you are flexible, say so: "Nominal 2x6, actual can vary."
Specify Minimum and Maximum Lengths
Reclaimed lumber comes in random lengths. Tell us your minimum usable length and your preferred maximum. For example: "Minimum 6 feet, prefer 8 to 12 feet, will accept random lengths within that range." If you need an exact length — say, for a mantel or countertop — state it explicitly and we will select and cut to order.
Indicate Surface Finish Requirements
Do you need rough-sawn (as-is), surfaced two sides (S2S), surfaced four sides (S4S), or a custom profile (T&G, shiplap, etc.)? The surfacing level directly affects the final thickness and width. A rough 2" board surfaced to S4S will lose approximately 3/16" per face, finishing around 1-5/8" thick.
Note Your Tolerance Requirements
If you are matching existing trim, fitting into an existing frame, or using CNC joinery that requires precision, tell us your acceptable tolerance range. We can sort and remilll to tighter specifications, but we need to know before pulling stock.
Specify Species and Acceptable Alternatives
If you need White Oak specifically, say so. If you would also accept Red Oak or mixed species, that flexibility helps us fill your order faster and often at a lower cost. List your first choice and any acceptable alternates.
Include the Application
Knowing whether the lumber is for flooring, framing, furniture, or a feature wall helps us select the most appropriate stock. Structural applications require different grading criteria than purely decorative ones. A brief description of the project helps us make better selections.
Example Order Specification
Species: White Oak (will also accept Red Oak)
Quantity: 300 board feet
Dimensions: Nominal 1x6, need actual thickness minimum 3/4", width minimum 5-1/4"
Lengths: Random, minimum 4 ft, prefer 6-10 ft
Surface: S4S, tongue and groove profile
Tolerance: Thickness +/- 1/32" for T&G fit
Application: Flooring in residential dining room, will be finished with polyurethane on site
Common Mistakes When Ordering Dimensional Lumber
We have filled thousands of reclaimed lumber orders over the years. These are the six mistakes we see most often — and each one is entirely avoidable with a little planning.
1. Assuming Nominal Equals Actual
This is the number one mistake. A customer orders "2x4s" expecting boards that measure exactly 2" x 4" and is surprised to receive modern-dimensioned boards at 1-1/2" x 3-1/2" — or true-dimension reclaimed at a full 2" x 4" when they needed modern dimensions to match existing framing. Always specify whether you need nominal or actual measurements.
2. Not Accounting for Surfacing Loss
Planing removes material — typically 1/16" to 1/8" per pass per face. If you order a rough 1" board and request S2S (surfaced two sides), the finished thickness will be approximately 13/16" to 7/8". If that finished thickness is critical to your project, specify the final dimension you need and let us select appropriately thick rough stock.
3. Ordering Too Little Material
Reclaimed lumber batches are unique. If you run short mid-project, the next available batch may differ in color, patina, or exact dimensions. Always add a 10-15% waste and safety margin to your calculated quantity. For complex installations like herringbone flooring, add 20%. The small extra cost is far less painful than trying to match material mid-project.
4. Mixing Reclaimed and Modern Without Testing
Reclaimed boards are often true dimension (thicker and wider than modern equivalents). If you plan to use reclaimed and modern lumber in the same assembly, test the fit of both before committing. A reclaimed 2x4 at 2" thick will not sit flush with a modern 2x4 at 1-1/2" thick. You may need to have the reclaimed stock milled down to match, or use shims.
5. Ignoring Moisture Content
Lumber dimensions change with moisture content. A board measured at 12% MC in our warehouse may measure slightly smaller after it acclimates to a dry, heated interior at 6-7% MC. Always acclimate lumber at the job site for a minimum of 3-7 days before installation, and use a moisture meter to confirm equilibrium before cutting.
6. Specifying Only Length Without Width and Thickness
Some customers order "fifty 8-foot boards" without specifying the cross-section dimensions they need. This creates ambiguity that leads to wrong shipments. Always specify all three dimensions: thickness, width, and length. If lengths can be random, say so — and state the minimum and maximum acceptable lengths. A complete specification eliminates guesswork and delays.