Lumber Size Guide
Complete reference for nominal vs. actual dimensions, board feet, weight tables, coverage calculations, and metric conversions.
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Nominal vs. Actual Sizes
Lumber is sold by its “nominal” size, which is larger than its actual dimension. This is because lumber shrinks during the drying and planing process. For example, a “2x4” actually measures 1-1/2” x 3-1/2”. The nominal size refers to the rough-sawn dimension before the board is dried and surfaced (planed smooth).
Reclaimed Lumber Note: Reclaimed lumber often comes in true nominal sizes (a reclaimed 2x4 may actually be 2” x 4”), which is one of its advantages. This is because much older lumber was sold at its rough-sawn dimensions before modern sizing standards were adopted in 1964. If you are replacing existing framing in an older structure, reclaimed lumber often matches the original dimensions perfectly.
Always verify: Whether buying new or reclaimed, always measure the actual dimensions of lumber before purchasing. Bring a tape measure to the yard, and check multiple pieces in a batch since dimensions can vary, especially in reclaimed stock.
Quick Navigation
Standard Softwood Dimensional Lumber
Softwood dimensional lumber includes pine, fir, spruce, and cedar. These are the most commonly available sizes at lumber yards. All actual dimensions follow the American Lumber Standard (ALS) established by the U.S. Department of Commerce.
| Nominal Size | Actual Size (inches) | Metric (mm) | BF per Linear Foot |
|---|---|---|---|
| 1 x 2 | 3/4" x 1-1/2" | 19 x 38 mm | 0.167 |
| 1 x 3 | 3/4" x 2-1/2" | 19 x 64 mm | 0.25 |
| 1 x 4 | 3/4" x 3-1/2" | 19 x 89 mm | 0.333 |
| 1 x 6 | 3/4" x 5-1/2" | 19 x 140 mm | 0.5 |
| 1 x 8 | 3/4" x 7-1/4" | 19 x 184 mm | 0.667 |
| 1 x 10 | 3/4" x 9-1/4" | 19 x 235 mm | 0.833 |
| 1 x 12 | 3/4" x 11-1/4" | 19 x 286 mm | 1 |
| 2 x 2 | 1-1/2" x 1-1/2" | 38 x 38 mm | 0.333 |
| 2 x 3 | 1-1/2" x 2-1/2" | 38 x 64 mm | 0.5 |
| 2 x 4 | 1-1/2" x 3-1/2" | 38 x 89 mm | 0.667 |
| 2 x 6 | 1-1/2" x 5-1/2" | 38 x 140 mm | 1 |
| 2 x 8 | 1-1/2" x 7-1/4" | 38 x 184 mm | 1.333 |
| 2 x 10 | 1-1/2" x 9-1/4" | 38 x 235 mm | 1.667 |
| 2 x 12 | 1-1/2" x 11-1/4" | 38 x 286 mm | 2 |
* Board feet per linear foot is based on nominal dimensions. Actual BF yield may differ slightly. Standard lengths: 8', 10', 12', 14', 16', 18', 20'.
Hardwood Lumber Thickness (Quarter System)
Hardwood lumber uses the “quarter system” for thickness, expressed in quarters of an inch. For example, 4/4 means four quarters, or 1 inch thick (rough). After surfacing (planing on both sides, called S2S), the board loses approximately 3/16” of thickness. Widths and lengths are random and sold by the board foot.
| Rough Thickness | Surfaced (S2S) | Metric Approx. | Common Uses |
|---|---|---|---|
| 4/4 (1") | 13/16" | 20.6 mm | Standard board thickness |
| 5/4 (1-1/4") | 1-1/16" | 27 mm | Decking, heavier trim |
| 6/4 (1-1/2") | 1-5/16" | 33 mm | Tabletops, counters |
| 8/4 (2") | 1-3/4" | 44 mm | Thick tops, turning blanks |
| 10/4 (2-1/2") | 2-3/16" | 56 mm | Heavy table legs, mantels |
| 12/4 (3") | 2-3/4" | 70 mm | Thick mantels, structural |
| 16/4 (4") | 3-3/4" | 95 mm | Turning stock, timber frame |
Reclaimed Hardwood Tip: Reclaimed hardwood is often thicker than modern surfaced dimensions because it was milled to true measurements. A reclaimed 4/4 oak board may be a full 1” thick. This extra thickness gives you more flexibility for planing and sanding to a clean finish while still maintaining good stock thickness.
Structural Timber Sizes
Timbers are lumber pieces 5” or larger in their smallest dimension. They are used for structural posts, beams, and heavy-duty construction. Reclaimed timbers from old warehouses, barns, and industrial buildings are especially prized for their old-growth density and dramatic character.
| Nominal | Actual | Metric | Common Use | BF/LF |
|---|---|---|---|---|
| 4 x 4 | 3-1/2" x 3-1/2" | 89 x 89 mm | Fence posts, light posts | 1.333 |
| 4 x 6 | 3-1/2" x 5-1/2" | 89 x 140 mm | Beams, rails, headers | 2 |
| 6 x 6 | 5-1/2" x 5-1/2" | 140 x 140 mm | Posts, columns, pergolas | 3 |
| 6 x 8 | 5-1/2" x 7-1/2" | 140 x 190 mm | Beams, headers | 4 |
| 6 x 10 | 5-1/2" x 9-1/2" | 140 x 241 mm | Beams, girders | 5 |
| 6 x 12 | 5-1/2" x 11-1/2" | 140 x 292 mm | Heavy beams, ridge beams | 6 |
| 8 x 8 | 7-1/2" x 7-1/2" | 190 x 190 mm | Large posts, columns | 5.333 |
| 8 x 10 | 7-1/2" x 9-1/2" | 190 x 241 mm | Heavy beams | 6.667 |
| 8 x 12 | 7-1/2" x 11-1/2" | 190 x 292 mm | Major structural beams | 8 |
| 10 x 10 | 9-1/2" x 9-1/2" | 241 x 241 mm | Large columns, posts | 8.333 |
| 10 x 12 | 9-1/2" x 11-1/2" | 241 x 292 mm | Major beams, bridges | 10 |
| 12 x 12 | 11-1/2" x 11-1/2" | 292 x 292 mm | Major structural elements | 12 |
Specialty Profiles & Siding
Profiled lumber (tongue and groove, shiplap, beadboard, etc.) has a reduced face width compared to the nominal board width because material is removed to create the profile. When calculating coverage, always use the exposed face width, not the nominal board width.
| Profile Type | Available Sizes | Exposed Face Width | Notes |
|---|---|---|---|
| Tongue & Groove (T&G) | 1x4, 1x6, 1x8 | 3", 5", 6-3/4" | Subtract ~1/2" from width for tongue |
| Shiplap | 1x6, 1x8, 1x10 | 5", 6-3/4", 8-3/4" | Overlap reduces coverage by ~1/2" |
| Beadboard | 1x4, 1x6 | 3-1/8", 5-1/8" | Decorative bead reduces face width |
| Barn Siding (Board & Batten) | 1x10 + 1x3 battens | Varies | Boards spaced ~1/4" apart with batten overlay |
| Live Edge Slabs | 2" to 4" thick | 12" to 48"+ wide | Natural irregular edges, width varies along length |
| Ship Decking | 2x6, 3x6, 3x8 | 5-1/2", 5-1/2", 7-1/2" | Often reclaimed from maritime vessels |
Coverage Calculation for Profiled Boards
To calculate how many linear feet of shiplap or T&G you need for a wall:
Linear Feet Needed = (Wall Area in sq ft × 12) / Exposed Face Width in inches
Example: An 8' x 12' wall = 96 sq ft. Using 1x6 shiplap with a 5” exposed face: (96 × 12) / 5 = 230.4 LF. Add 15% waste factor = ~265 LF needed.
Plywood & Panel Sizes
Like dimensional lumber, plywood nominal thickness differs from actual thickness. Standard sheets are 4' x 8' (48” x 96”). Specialty sizes include 4'x4', 4'x10', and 5'x5' panels. We carry reclaimed plywood and repurposed panel products when available.
| Nominal Thickness | Actual Thickness | Metric | Approx. Weight (4x8) | Sheet Size |
|---|---|---|---|---|
| 1/4" | 0.230" | 5.8 mm | 22 lbs | 4'x8' |
| 3/8" | 0.354" | 9.0 mm | 29 lbs | 4'x8' |
| 1/2" | 0.468" | 11.9 mm | 40 lbs | 4'x8' |
| 5/8" | 0.578" | 14.7 mm | 48 lbs | 4'x8' |
| 3/4" | 0.703" | 17.9 mm | 60 lbs | 4'x8' |
| 1" | 0.953" | 24.2 mm | 80 lbs | 4'x8' |
| 1-1/8" | 1.078" | 27.4 mm | 90 lbs | 4'x8' |
Weight Per Board Foot by Species
Knowing the weight of different species is essential for structural planning, shipping calculations, and choosing the right wood for your project. Weights listed are approximate and vary with moisture content. Dried weight assumes 12% MC. Janka hardness (lbf) indicates dent resistance — higher numbers mean harder wood.
| Species | Category | Dried (lbs/BF) | Green (lbs/BF) | Specific Gravity | Janka Hardness |
|---|---|---|---|---|---|
| Balsa | Softwood | 0.7 | 1.3 | 0.16 | 100 |
| Western Red Cedar | Softwood | 1.9 | 2.9 | 0.32 | 350 |
| Redwood | Softwood | 2.3 | 4.4 | 0.35 | 420 |
| White Pine | Softwood | 2.1 | 4 | 0.35 | 380 |
| Sugar Pine | Softwood | 2.1 | 4.2 | 0.36 | 380 |
| Sitka Spruce | Softwood | 2.3 | 3.4 | 0.36 | 510 |
| Ponderosa Pine | Softwood | 2.4 | 4.5 | 0.4 | 460 |
| Douglas Fir | Softwood | 2.8 | 4.5 | 0.48 | 660 |
| Southern Yellow Pine | Softwood | 3.1 | 5.2 | 0.51 | 690 |
| Poplar / Tulipwood | Hardwood | 2.5 | 4.5 | 0.42 | 540 |
| Black Walnut | Hardwood | 3.2 | 4.9 | 0.55 | 1010 |
| American Cherry | Hardwood | 2.9 | 4.5 | 0.5 | 950 |
| American Chestnut | Hardwood | 2.7 | 4.8 | 0.43 | 540 |
| Red Oak | Hardwood | 3.4 | 5.6 | 0.56 | 1290 |
| White Oak | Hardwood | 3.8 | 5.8 | 0.6 | 1360 |
| Hard Maple | Hardwood | 3.6 | 5.5 | 0.63 | 1450 |
| Ash | Hardwood | 3.4 | 4.8 | 0.55 | 1320 |
| Hickory | Hardwood | 4.2 | 5.8 | 0.66 | 1820 |
| Ipe (Ironwood) | Tropical Hardwood | 5.7 | 7.2 | 0.91 | 3684 |
Shipping Weight Estimate: To estimate the total weight of an order, multiply the board feet by the dried weight per BF for your species. For example, 200 BF of dried Red Oak: 200 × 3.4 = ~680 lbs. Always add 10-15% for moisture variation. Our delivery trucks can handle up to 8,000 lbs per load.
How to Calculate Board Feet
A board foot (BF) is the standard unit of measurement for lumber volume in the United States. One board foot equals a piece of wood 12 inches long, 12 inches wide, and 1 inch thick (144 cubic inches total). Board foot pricing is the industry standard for hardwoods and specialty lumber. Dimensional softwood (2x4s, 2x6s, etc.) is often sold by the linear foot, but understanding board feet is still essential for comparing value.
Formula:
Board Feet = (Thickness” × Width” × Length') / 12
Use nominal dimensions for thickness and width. Length is always in feet. When buying hardwood by the board foot, thickness uses the quarter system (4/4 = 1”, 8/4 = 2”, etc.).
Alternative Formula (all inches):
Board Feet = (Thickness” × Width” × Length”) / 144
Common Board Foot Calculations
| Board Description | Calculation | Result |
|---|---|---|
| 2x4, 8 feet long | (2 x 4 x 8) / 12 | 5.33 BF |
| 2x6, 12 feet long | (2 x 6 x 12) / 12 | 12 BF |
| 2x8, 10 feet long | (2 x 8 x 10) / 12 | 13.33 BF |
| 2x10, 16 feet long | (2 x 10 x 16) / 12 | 26.67 BF |
| 2x12, 14 feet long | (2 x 12 x 14) / 12 | 28 BF |
| 1x6, 8 feet long | (1 x 6 x 8) / 12 | 4 BF |
| 1x12, 10 feet long | (1 x 12 x 10) / 12 | 10 BF |
| 4x4, 8 feet long | (4 x 4 x 8) / 12 | 10.67 BF |
| 6x6, 10 feet long | (6 x 6 x 10) / 12 | 30 BF |
| 8x8, 12 feet long | (8 x 8 x 12) / 12 | 64 BF |
Standard Lengths
Softwood lumber is commonly available in 2-foot increments from 8' to 20'. Some yards stock 6' lengths. Longer lengths (22', 24') are available by special order. Hardwood is sold in random lengths, typically 4' to 16'.
Reclaimed Lumber Sizing
Reclaimed lumber may be full-dimension (true 2x4 = actually 2”x4”) unlike modern lumber. Lengths are non-standard and vary by source. Always verify actual dimensions and plan for variable lengths when working with reclaimed stock.
Linear Foot vs. Board Foot
A linear foot measures length only (12 inches). A board foot measures volume (thickness × width × length). A 2x6 that is 1 linear foot long contains 1 board foot of wood. These units are not interchangeable.
Square Foot Coverage
For wall/floor coverage, 1 BF of 1”-thick lumber covers 1 square foot. For thicker stock, divide BF by thickness in inches to get square footage. Always add 10-15% for waste, cuts, and defects when estimating material needs.
Common Project Quantity Estimates
Use these estimates as starting points for material planning. Actual quantities will vary based on your specific design, waste factor, and lumber dimensions. We recommend adding 10-15% to all estimates for cuts, waste, and defects. Our team can help you create a precise material list for your project.
| Project | Materials | Est. Board Feet | Est. Linear Feet | Notes |
|---|---|---|---|---|
| Deck (12' x 16') | 2x6 decking, 2x8 joists, 4x4 posts | 350-450 BF | ~500 LF | Includes framing; add 10-15% waste factor |
| Deck (16' x 20') | 2x6 decking, 2x10 joists, 6x6 posts | 600-750 BF | ~800 LF | Larger spans need bigger joists |
| Privacy Fence (6' tall, 50 LF) | 1x6 pickets, 2x4 rails, 4x4 posts | 200-250 BF | ~350 LF | Posts every 8'; 3 rails per section |
| Privacy Fence (6' tall, 100 LF) | 1x6 pickets, 2x4 rails, 4x4 posts | 400-500 BF | ~700 LF | Double the 50 LF estimate |
| Accent Wall (8' x 12') | 1x4, 1x6, 1x8 mixed barn wood | 80-100 BF | ~120-160 LF | Mixed widths look best; add 15% for cuts |
| Accent Wall (8' x 16') | 1x4, 1x6, 1x8 mixed barn wood | 105-130 BF | ~160-210 LF | Larger walls; stagger joints |
| Floating Shelves (3 shelves, 4' each) | 2x10 or 2x12 | 20-30 BF | 12 LF | Thick stock for substantial look |
| Dining Table (3.5' x 7') | 8/4 hardwood, 4x4 legs | 30-40 BF | N/A | Depends on slab vs. glue-up construction |
| Farmhouse Table (4' x 8') | 8/4 hardwood top, 4x4 legs, 2x6 stretchers | 45-55 BF | N/A | Thick top with trestle base |
| Raised Garden Bed (4' x 8' x 18") | 2x6 cedar or redwood | 50-60 BF | ~60 LF | Use naturally rot-resistant species |
| Pergola (10' x 12') | 6x6 posts, 2x8 rafters, 2x6 crossbeams | 250-300 BF | ~150 LF | 4 posts minimum; double beams for strength |
| Barn Door (3' x 7') | 1x6 T&G boards, 1x6 Z-frame | 25-35 BF | ~40 LF | Plus hardware kit; reclaimed wood ideal |
| Wainscoting (50 LF, 3' height) | 1x4 beadboard or shiplap | 50-65 BF | ~150-200 LF | Chair rail and baseboard extra |
| Shiplap Full Wall (8' x 20') | 1x6 or 1x8 shiplap boards | 130-160 BF | ~250-320 LF | Account for overlap loss; add 15% for waste |
Free Material Estimates
Need a precise material list? Bring your project plans or measurements to our South LA yard, and our team will help you calculate exactly what you need. We offer free material estimates for all projects and can help you choose the right species, grade, and dimensions. Email us at info@losangeles-lumber.com or visit during business hours.
Metric Conversion Reference
For international projects, architectural specifications in metric, or when working with imported materials, use these conversions. Los Angeles sees many projects that require metric specifications, especially in commercial and institutional construction.
| Imperial | Metric | Decimal Metric |
|---|---|---|
| 1 inch | 25.4 mm | 2.54 cm |
| 1 foot | 304.8 mm | 30.48 cm |
| 1 yard | 914.4 mm | 0.914 m |
| 1 board foot | 2,359.7 cm³ | 0.00236 m³ |
| 1 square foot | 929 cm² | 0.0929 m² |
| 1 cubic foot | 28,317 cm³ | 0.0283 m³ |
| 1 pound | 453.6 g | 0.454 kg |
| 1 lb/ft³ | 16.02 kg/m³ |
Fraction — Decimal — Millimeter Conversion Chart
Lumber dimensions use fractions of an inch. This chart converts common fractions to decimal inches and millimeters for precise measurements and tool setup.
| Fraction (inches) | Decimal (inches) | Millimeters |
|---|---|---|
| 1/16" | 0.0625" | 1.59 mm |
| 1/8" | 0.125" | 3.18 mm |
| 3/16" | 0.1875" | 4.76 mm |
| 1/4" | 0.250" | 6.35 mm |
| 5/16" | 0.3125" | 7.94 mm |
| 3/8" | 0.375" | 9.53 mm |
| 7/16" | 0.4375" | 11.11 mm |
| 1/2" | 0.500" | 12.70 mm |
| 9/16" | 0.5625" | 14.29 mm |
| 5/8" | 0.625" | 15.88 mm |
| 11/16" | 0.6875" | 17.46 mm |
| 3/4" | 0.750" | 19.05 mm |
| 13/16" | 0.8125" | 20.64 mm |
| 7/8" | 0.875" | 22.23 mm |
| 15/16" | 0.9375" | 23.81 mm |
| 1" | 1.000" | 25.40 mm |
Moisture Content & Dimensional Stability
Wood is hygroscopic — it absorbs and releases moisture from the surrounding environment. As moisture content (MC) changes, wood expands and contracts primarily across the grain (width and thickness). Understanding moisture behavior is critical for avoiding gaps, warping, cupping, and other defects in finished projects. In Southern California's arid climate, interior equilibrium moisture content (EMC) is typically 6-8%.
| Moisture Content | Condition | Dimensional Change | Application Notes |
|---|---|---|---|
| 6-8% | Kiln Dried / Interior | Baseline (optimal for interior use) | Ideal for flooring, furniture, cabinetry, trim. Standard for Los Angeles interiors. |
| 9-12% | Air Dried | +1-2% width expansion | May shrink slightly when brought indoors in SoCal dry climate. Acceptable for rough construction. |
| 12-15% | Covered Exterior | +2-3% width expansion | Good for covered outdoor applications. Typical EMC for shaded exterior in coastal LA. |
| 15-19% | Green / Undried | +3-5% width expansion | Needs further drying before interior use. Risk of warping, cupping, and checking. |
| 19-30%+ | Freshly Sawn / Wet | +5-10%+ width expansion | Requires extensive drying. Not suitable for finish work. Expect significant shrinkage. |
Tangential vs. Radial Shrinkage
Wood shrinks approximately twice as much tangentially (along the growth rings) as radially (across the rings). This is why quarter-sawn lumber is more dimensionally stable than flat-sawn. A flat-sawn 1x12 can shrink up to 1/4” in width across a 10% MC change, while a quarter-sawn board of the same width may shrink only 1/8”.
Acclimation Best Practices
Before installing any lumber indoors, allow it to acclimate in the target environment for at least 5-7 days (ideally 2 weeks for flooring). Stack boards with stickers between layers for air circulation. Check MC with a moisture meter before installation — it should be within 2% of the target EMC for your space.
Reclaimed Lumber Sizing: What to Expect
Reclaimed lumber behaves differently from new, standardized lumber. Understanding these differences will help you plan more effectively and get the most out of your reclaimed materials.
True Nominal Dimensions
Pre-1964 lumber was sold at actual rough-sawn dimensions. A reclaimed 2x4 from this era is actually 2" x 4", giving you 33% more wood than a modern 2x4. This is especially valuable for heavy-timber construction and restoration projects.
Non-Standard Lengths
Reclaimed boards come in whatever lengths they were cut or salvaged at. Expect random lengths from 2' to 20'+. Plan for variable lengths and order extra to allow for selective cutting and matching.
Width Variation
Unlike modern lumber that is uniform, reclaimed boards may vary in width by 1/8" to 1/4" even within the same nominal size. Always measure each piece and sort by actual width before layout.
Thickness After Resurfacing
If you plan to have reclaimed lumber planed smooth, expect to lose 1/16" to 1/8" per side (1/8" to 1/4" total). Start with slightly thicker stock than your target finished dimension.
Old-Growth vs. New-Growth
Old-growth reclaimed lumber (tight, even grain) is typically denser and heavier than new-growth lumber of the same species. Account for the extra weight in structural calculations and shipping estimates.
Moisture Content Variability
Reclaimed lumber MC varies widely depending on storage conditions. Wood from a dry barn may be at 8%, while outdoor-stored salvage could be 20%+. Always meter test before purchasing and allow acclimation time.
Need Help Sizing Your Project?
Our team has decades of experience working with reclaimed lumber of every type and origin. We can help you navigate the sizing differences, select the right material for your application, and calculate accurate material quantities. Visit us at our South LA yard, call during business hours, or email info@losangeles-lumber.com with your project details. We are happy to provide free estimates and material recommendations.