Why This Matters
Lumber Sizing Is More Complex Than You Think
Whether you are framing a new wall, installing reclaimed flooring, or building custom furniture, understanding lumber sizes is the foundation of every successful project. Ordering the wrong size wastes money, delays timelines, and creates frustrating rework. Yet lumber sizing remains one of the most misunderstood aspects of construction and woodworking.
The confusion starts with the fact that the lumber industry uses a "nominal" naming convention that does not correspond to the actual physical dimensions of the board. A "2x4" is not 2 inches by 4 inches — it is 1-1/2 inches by 3-1/2 inches. This discrepancy exists because the nominal name refers to the rough-sawn dimension before the board is kiln-dried and surfaced (planed smooth). The drying process shrinks the wood, and the planing process removes additional material, resulting in a finished board that is significantly smaller than its name suggests.
The American Lumber Standard Committee (ALSC) formalized these standards in 1964. Since then, every piece of dimensional softwood lumber sold in the United States follows the same nominal-to-actual conversion. However, hardwood lumber uses an entirely different system based on quarter-inch thickness increments (4/4, 5/4, 6/4, 8/4), adding another layer of complexity.
Reclaimed lumber introduces yet another variable. Much of the wood we sell at New York Lumber was milled decades or even a century before modern sizing standards existed. This means reclaimed boards are frequently "true" to their nominal dimensions — a reclaimed 2x4 often measures a full 2 inches by 4 inches, giving you roughly 30% more material than a modern board with the same name. This is one of the great, often-overlooked advantages of working with reclaimed wood.
How Reclaimed Lumber Sizing Differs from New
True Dimensions
Pre-1964 lumber was not subject to today's sizing standards. Most reclaimed boards were cut to their full nominal size and left unsurfaced, or were hand-planed with minimal material removal. A reclaimed 2x6 typically measures a full 2" x 6", compared to a modern 2x6 at 1-1/2" x 5-1/2".
Dimensional Variability
Reclaimed pieces may vary slightly from board to board because they were hand-sawn or processed on less precise equipment. Expect tolerances of +/- 1/8" on thickness and width. Always measure individual pieces before committing to a design that requires exact uniformity.
Unique Sizes Available
Reclaimed sources often yield dimensions that are no longer commonly milled, such as true 1x3, 3x8, 3x10, or massive 12x12 timbers. These sizes are ideal for restoration projects, historic renovations, and custom architectural features where modern equivalents simply do not exist.
Re-Milling Options
If you need reclaimed wood milled to specific modern dimensions, our on-site mill can surface, rip, and plane any piece to your exact specifications. This lets you combine the character and sustainability of reclaimed wood with the precision of modern construction standards.
Quick Reference: Nominal vs. Actual
The table below shows the most common dimensional lumber sizes, comparing what the name says, what you actually receive from a modern lumber yard, and what you can typically expect from our reclaimed inventory.
| Nominal Size | Actual Size (New Lumber) | Reclaimed (May Vary) |
|---|---|---|
| 1x2 | 3/4" x 1-1/2" | Often true 1" x 2" |
| 1x3 | 3/4" x 2-1/2" | Often true 1" x 3" |
| 1x4 | 3/4" x 3-1/2" | Often true 1" x 4" |
| 1x6 | 3/4" x 5-1/2" | Often true 1" x 6" |
| 1x8 | 3/4" x 7-1/4" | Often true 1" x 8" |
| 1x10 | 3/4" x 9-1/4" | Often true 1" x 10" |
| 1x12 | 3/4" x 11-1/4" | Often true 1" x 12" |
| 2x4 | 1-1/2" x 3-1/2" | Often true 2" x 4" |
| 2x6 | 1-1/2" x 5-1/2" | Often true 2" x 6" |
| 2x8 | 1-1/2" x 7-1/4" | Often true 2" x 8" |
| 2x10 | 1-1/2" x 9-1/4" | Often true 2" x 10" |
| 2x12 | 1-1/2" x 11-1/4" | Often true 2" x 12" |
| 4x4 | 3-1/2" x 3-1/2" | Often true 4" x 4" |
| 6x6 | 5-1/2" x 5-1/2" | Often true 6" x 6" |
| 8x8 | 7-1/4" x 7-1/4" | Often true 8" x 8" |
Note: One major advantage of reclaimed lumber is that older wood was often cut to "true" dimensions. A reclaimed 2x4 is often a full 2 inches by 4 inches — significantly more material than modern dimensional lumber. This extra thickness and width can affect your project calculations, so always confirm measurements before finalizing your plans.
Preparation
Measurement Tools You Will Need
Accurate measurements are the difference between a project that goes smoothly and one that requires costly returns and reorders. We recommend keeping these tools on hand whenever you are selecting or inspecting lumber.
Tape Measure (25 ft minimum)
Essential for measuring length, width, and thickness. Choose one with both imperial and metric markings. A 25-foot tape covers most board lengths.
Combination Square
Checks squareness, measures depth, and verifies that boards are true. Invaluable when working with reclaimed wood that may have slight irregularities.
Digital Calipers
Provides precise thickness measurements to 1/1000 of an inch. Critical when you need exact dimensions for joinery, tongue-and-groove installation, or matching existing millwork.
Moisture Meter
Measures the moisture content of wood. Reclaimed lumber should be below 12% for interior projects and below 19% for exterior use. High moisture causes warping and shrinkage after installation.
Straightedge (4-6 ft)
Place along the length of a board to check for bowing, cupping, or twisting. A long aluminum straightedge or even a factory-edge piece of plywood works well.
Board Foot Calculator
Our free online calculator or a simple smartphone app lets you quickly convert dimensions into board feet for accurate ordering and cost estimation.
Avoid These Errors
Common Mistakes When Ordering Lumber
Even experienced builders make sizing mistakes. Here are the most frequent issues we see and how to avoid them.
Assuming nominal equals actual
Always reference the actual dimensions chart. A 2x4 is only 1-1/2" x 3-1/2" in modern lumber. If your design requires a full 2" x 4", specify reclaimed or request re-milling to exact dimensions.
Not accounting for the wastage factor
Plan for 10-15% extra material to cover cuts, defects, and fitting waste. For complex layouts like herringbone flooring, add 20%. Reclaimed wood may have sections that need to be cut around nail holes or checking.
Mixing reclaimed and modern lumber without measuring
Reclaimed boards are often thicker and wider than modern equivalents. If you mix the two, you will get uneven surfaces and misaligned joints. Always measure both types and plan for shimming or planing.
Confusing board feet with square feet or linear feet
Board feet measure volume (thickness x width x length / 144). Square feet measure area (width x length). Linear feet measure only length. Pricing and quantities use different units — always confirm which unit a quote uses.
Ordering by nominal dimensions for tight-tolerance work
For cabinetry, fine furniture, and precision joinery, always specify exact finished dimensions in inches, not nominal sizes. Provide drawings or cut lists with actual measurements.
Ignoring moisture content
Wood that is too wet will shrink as it dries, opening joints and causing gaps. Wood that is too dry may absorb moisture and swell. Ask about moisture content before purchasing, especially for flooring and trim.
Not inspecting boards before leaving the yard
Check for bowing, cupping, twisting, and excessive defects before loading. It is much easier to swap a board in the yard than after you have transported it to your job site.
Pro Tips
Tips for Ordering the Right Size Every Time
Step 1: Create a Detailed Cut List
Before ordering, list every piece you need with its exact finished dimensions (thickness x width x length). Include the quantity of each piece. Group by dimension to identify what stock sizes you need to order.
Step 2: Add Your Waste Factor
Add 10% for straightforward projects (framing, shelving). Add 15% for projects with angled cuts (deck boards, siding). Add 20% for complex patterns (herringbone, parquet). Reclaimed wood may need extra to account for sections with nail holes or damage.
Step 3: Convert to Board Feet
Use our board foot calculator to convert your cut list into total board feet. This is the standard unit for pricing lumber and will let you compare quotes accurately. Remember: board feet = (thickness x width x length) / 144, where all measurements are in inches.
Step 4: Specify Reclaimed or New
When mixing sources, clearly mark which pieces should be reclaimed and which can be new. Remember that reclaimed boards are typically larger at the same nominal size, so your board foot totals will be slightly different for the same project.
Step 5: Communicate Species and Grade
Different species and grades have different costs, appearances, and structural properties. Specifying these upfront avoids surprises. If you are unsure, our team can recommend the best option for your application and budget.
Step 6: Request Samples for Large Orders
For orders over 500 board feet or for visible applications like flooring and wall cladding, request a sample set before committing. We are happy to set aside representative pieces so you can verify color, grain, dimensions, and character before your full order ships.
Quick Conversions
Lumber Measurement Conversions
Different measurement units are used depending on the context. Here is a quick-reference comparison to help you move between the most common units.
Linear Foot (LF)
Measures length only, regardless of width or thickness. One linear foot = 12 inches of board length. Used for trim, molding, and material sold by the running foot.
Board Foot (BF)
Measures volume. One board foot = a piece 1" thick x 12" wide x 12" long (144 cubic inches). The standard pricing unit for rough lumber. Accounts for thickness, width, and length simultaneously.
Square Foot (SF)
Measures area coverage, ignoring thickness. One square foot = 144 square inches. Used for flooring, siding, paneling, and other products sold by coverage area.
| Imperial | Metric Equivalent |
|---|---|
| 1 inch | 25.4 mm (2.54 cm) |
| 1 foot (12 inches) | 304.8 mm (30.48 cm) |
| 1 board foot | 2,359.74 cm3 (0.00236 m3) |
| 1 square foot | 929.03 cm2 (0.0929 m2) |
| 1/4 inch | 6.35 mm |
| 1/2 inch | 12.7 mm |
| 3/4 inch | 19.05 mm |
| 1-1/2 inches | 38.1 mm |
| 3-1/2 inches | 88.9 mm |
| 5-1/2 inches | 139.7 mm |
Explore Further
Dive Deeper
Dimensional Lumber Guide
Complete reference for standard and reclaimed lumber dimensions with comparison charts covering every common size from 1x2 through 12x12. Includes softwood and hardwood conventions, metric conversions, and tolerance expectations.
View full chart →Board Foot Calculator
Interactive tool to calculate board feet, estimate costs, and plan your lumber order. Includes detailed explanations, common conversion tables, pricing examples by species, wastage factor guidelines, and tips for measuring irregular reclaimed pieces.
Calculate now →Grading Standards
Understand lumber grades from Select Structural to #3 Common, both for new and reclaimed wood. Covers NHLA hardwood grading, defect types (knots, checks, splits, wane), grade selection by project type, and cost implications of your grade choice.
Learn grades →