Why 2x4x8 Lumber Doesn’t Measure 2 inches by 4 inches by 8 inches

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The numbers 2x4x8 are a bit of a misnomer. When measured, 2x4x8 lumber isn’t actually 2 inches by 4 inches by 8 inches. So, why is that? In this post, we’ll explore everything you need to know about 2x4x8 lumber measurements to help you determine what lumber to buy.

Table of Contents

What Do the Different Wood Size Numbers Denote?

Comparing Nominal and Actual Dimensions

Comparing Nominal and Dimensional Lumber

Common Dimensional Lumber Measurements

Final Word

What Do the Different Wood Size Numbers Denote?

Woodwork boards are available in various sizes. Some common sizes for home projects include 2x4x8, 2x6x10, 2x8x10, and 4x4x10. These numbers refer to the thickness, width, and lengths of the boards, respectively. The thickness and width are measured in inches, while the length is measured in feet.

However, if you measure a 2x4x8, you’ll be surprised to find it doesn’t actually measure 2 inches by 4 inches by 8 feet. Instead, it’s usually about 1.5 inches by 3.5 inches by 8 feet. So, why are the measurements misleading? Well, they aren’t. The varying measurements come about because of the difference between nominal and actual dimensions.

Comparing Nominal and Actual Dimensions

2x4x8 lumber is named for its nominal dimensions. The boards you’ll come across at local hardware stores, home improvement stores, and online use nominal dimensions. Nominal dimensions are the raw, undressed dimensions of lumber before it has been dried, planed, or cut down to size.

On the other hand, the actual dimensions are the finished dimensions of lumber after it has been dried, planed, or cut down to size. When lumber is dried, it usually loses its moisture content and shrinks. As a result, there’s a reduction in the board’s size.

Pro tip: As a rule of thumb, if you want to determine the actual dimensions of most boards with a thickness of 2 inches, subtract 0.5 inches from the nominal thickness and 0.5 or 0.75 inches from the nominal width. Generally, you should subtract 0.5 inches from the nominal width of boards with widths ranging between 2 and 6 and 0.75 inches from boards with widths that are 8 inches and above.

Comparing Nominal and Dimensional Lumber

Nominal lumber is lumber that hasn’t been dried, planed, or cut down to its final dimensions. It usually isn’t available at hardware stores, home improvement stores, or online. However, you can find it at sawmills and lumber yards. Nominal lumber is primarily used for fine woodworking projects.

On the other hand, dimensional lumber is lumber that has been dried and cut down to its final dimensions. It’s the lumber you’ll find at hardware stores, home improvement stores, and online. Dimensional lumber is the most common type of lumber used by builders and DIYers because of its standard sizing.

When you buy dimensional lumber, you’ll find nominal measurements printed on the board. That means that if you buy a 2x4x8 board, you’ll get a board that measures 1.5 inches by 3.5 inches by 8 feet. So take this into account when buying lumber. 

Common Dimensional Lumber Measurements

Softwoods such as spruce, pine, and fir, typically used for framing projects, are sold in standard dimensional lumber sizes. However, it is important to note that hardwoods and plywoods don’t use the same standard dimensional lumber sizes as softwoods.

That said, here are the nominal and actual measurements for common dimensional boards with a thickness of 2 inches:

 

Nominal size (inches) Actual size (inches) Actual size (mm)
Two-by-two or 2×2 1-1/2 x 1-1/2 38 x 38
Two-by-three or 2×3 1-1/2 x 2-1/2 38 x 64 
Two-by-four or 2×4 1-1/2 x 3-1/2 38 x 89
Two-by-six or 2×6 1-1/2 x 5-1/2 38 x 140
Two-by-eight or 2×8 1-1/2 x 7-1/4 38 x 184
Two-by-ten or 2×10 1-1/2 x 9-1/4 38 x 235
Two-by-twelve or 2×12 1-1/2 x 11-1/4 38 x 286

Final Word

Lumber sizes can be confusing. If you’re confused between the different sizes, here are some key things to keep in mind when buying lumber:

 

  • Nominal stands for name. Nominal sizing is just a naming convention used for dimensional lumber. It doesn’t indicate the actual size of the boards. For example, 2x4x8.
  • The actual size is the real measurements you would get if you measured a board using a tape measure. The actual size usually isn’t indicated on boards.
  • Nominal lumber is lumber in its raw state. Lumber manufacturers haven’t dried or finished it. Conversely, dimensional lumber has been dried and finished. It’s usually lumber that’s ready to use, and it’s the preferred choice for most projects because of its standard sizing.
  • When dimensional lumber is cut down to size, only the thickness and width measurements are considered. The length is treated separately.
  • Nominal measurements are the naming standard for softwoods. They don’t apply to hardwoods and plywoods.
  • Also Read: Six Tips To Properly Preserve And Store The Food Of Our Dogs And Cats.

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