A lumber dimensions chart shows you the actual size of any nominal board — because a 2x4 is never really 2 inches by 4 inches. Nominal sizes are the rough-sawn dimensions before drying and planing; actual sizes are what you get at the lumber yard. Toggle between inches and millimeters to match your project's measurement system.
Cross-Section: Nominal vs Actual
Tap any row in the table to visualize the cross-section. The outer dashed box is the nominal size; the filled box is the actual size.
Nominal vs Actual Dimensions
| Nominal Size | Actual Size |
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No sizes found
Try searching for "2x4", "4x4", or clear the search
Board Foot Calculator
Formula: (thickness × width × length) / 144 — uses actual dimensions. Full calculator →
Weight Per Linear Foot (approx.)
Kiln-dried softwood (Douglas Fir / Southern Yellow Pine). Values vary by moisture content and species.
| Nominal Size | lbs / lin ft | kg / lin m |
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How to Use the Lumber Dimensions Chart
This free lumber dimensions chart lists the actual size of every standard dimensional lumber board in both inches and millimeters. Whether you're planning a deck, framing a wall, or building furniture, knowing the real dimensions prevents costly measurement errors.
Step 1: Choose Your Units
Click inches or mm to toggle between imperial and metric. The table and board foot calculator both update instantly. Inches are standard on US job sites; millimeters are standard in most other countries and are preferred for precision woodworking.
Step 2: Find Your Lumber Size
Type in the search box to filter by nominal size (e.g. "2x4", "4x4", "1x6"). You can also browse the full table. Click any row to see a visual cross-section diagram showing how much smaller the actual size is compared to the nominal name.
Step 3: Calculate Board Feet
Use the Board Foot Calculator below the table to estimate material volume and cost. Select a nominal size, enter the length and quantity, and optionally add a price per board foot. The calculator uses actual dimensions so your volume estimates are accurate.
Why Nominal ≠ Actual
When lumber is first cut at the sawmill, it is rough-sawn to the nominal size (e.g., 2×4 inches). It is then kiln-dried — which causes shrinkage — and run through a planer to create smooth, consistent surfaces. These two steps remove roughly 1/4 to 1/2 inch from each dimension. The nominal lumber dimensions chart sizes have been standardized since the 1960s: a 2×4 is always 1-1/2 × 3-1/2 inches, and a 1×6 is always 3/4 × 5-1/2 inches.
Common Lumber Sizes for Framing
2x4 (actual: 1.5 × 3.5 in) is the most common framing lumber, used for interior walls and partitions. 2x6 (actual: 1.5 × 5.5 in) is used for exterior walls where deeper insulation is required. 2x8, 2x10, 2x12 are used for floor joists, rafters, and headers — wider boards span longer distances with less deflection. 4x4 (actual: 3.5 × 3.5 in) is standard for fence posts and deck posts.
Standard Lumber Lengths
Dimensional lumber is sold in standard lengths: 8 ft, 10 ft, 12 ft, 16 ft, and 20 ft. Unlike the cross-section dimensions, the length is accurate — an 8-foot board is genuinely 96 inches long. For framing standard 8-foot ceilings, pre-cut studs are sold at 92-5/8 inches to account for the top and bottom plates.
FAQ
Is this lumber dimensions chart free?
Yes, completely free with no account required. All data is built into the page and works offline — nothing is sent to any server.
Is my data private?
Yes. Everything runs entirely in your browser. No data ever leaves your device.
Why is a 2x4 not actually 2 inches by 4 inches?
Nominal lumber sizes (like 2x4) reflect the rough-sawn dimensions before the wood is dried and planed. Drying causes shrinkage, and planing removes additional material for a smooth surface. The result is that a 2x4 measures 1.5 x 3.5 inches. This standard has been in place since the mid-20th century.
What are the actual dimensions of a 2x4?
A 2x4 measures 1-1/2 inches (38 mm) thick by 3-1/2 inches (89 mm) wide. The nominal '2x4' refers to its rough-sawn size before milling, not the finished dimension.
What are the actual dimensions of a 2x6?
A 2x6 measures 1-1/2 inches (38 mm) thick by 5-1/2 inches (140 mm) wide. Like all dimensional lumber, the actual size is smaller than the nominal size due to the drying and planing process.
What is a board foot and how do I calculate it?
A board foot is a unit of lumber volume equal to 144 cubic inches — a piece 1 inch thick, 12 inches wide, and 1 foot long. The formula is: board feet = (thickness in inches × width in inches × length in feet) / 12. For example, a 2x4 that is 8 feet long = (1.5 × 3.5 × 8) / 12 = 3.5 board feet.
Do lumber dimensions differ between softwood and hardwood?
The nominal-to-actual conversion described here applies to softwood dimensional lumber (pine, fir, spruce) sold at home improvement stores. Hardwood lumber is typically sold in rough-sawn form by the board foot, using quarter sizes (4/4, 5/4, 6/4) that represent thickness in quarter-inch increments. Hardwood actual sizes vary more depending on the supplier.
What common lengths does dimensional lumber come in?
Standard dimensional lumber lengths are 8, 10, 12, 14, 16, and 20 feet. The most common for framing are 8 and 16 feet. Length is the one dimension that is accurate — an 8-foot 2x4 is genuinely 96 inches long.