Are you working on a DIY or home improvement project involving buying lumber? Well, if you are new to buying hardwood or softwood lumber, there are a few things you need to know. One of these things is the dimensions of the lumber.
If you take a measuring tape to check the dimensions of the lumber you just bought, you will discover that they do not match the measurements the salesman at the hardware shop gave you.
You’ll also see that hardwood and softwood are standardized differently, which adds to the confusion. If you are confused due to timber’s various dimensions and standardizations, read on to clear your doubts.
What Is 2×8 Actual Size?
The actual size of 2×8 is 1 1/2 by 7 1/4 inches (38 x 184 mm) and not 2×8. 2×8 is the nominal size, the size of the lumber before the wood has been processed.
The nominal size is used for sales and advertising. It is also the commercial dimension used all over the country. Actual size is the size arrived at after the sawing, polishing, and finishing.
You may have noticed that the lumber yard or the hardware store that you bought your framing lumber or frame softwood from advertised different dimensions but gave you a smaller-sized board.
The board’s nominal dimensions, used in advertising and sales, are greater than its actual dimensions. The dimensional lumber is cut to a given length, depth, and width but only varies slightly from the actual size.
Lumber’s Actual Dimension and Size
A lumber’s actual dimension and size refer to its final dimensions after it goes through sawing and processing. The actual size of the finished product is slightly smaller than the nominal size.
When you buy softwood lumber, the lumber yard store will most probably give you dimensional lumber. Construction and framing projects mostly employ dimensional lumber.
This is lumber that has undergone milling and drying to obtain standard dimensions. Businesses market the lumber using its nominal dimensions instead of its actual size.
These were the board’s original dimensions before it went through milling and drying. So, as established before, the board is a bit smaller than the stated size. So a 2× 8 board is 1 ½ × 7 ¼, a 2× 4 is 1 ½ × 3 ½, and so on.
Basic Lumber Dimensions
The basic lumber dimensions refer to the depth and width of the material. For example, a two-by-eight or 2×8 refers to lumber that is 2 inches deep and 8 inches wide.
The dimension does not refer to the length of the lumber as the shrinkage is less pronounced longitudinally. So a 10-foot 2-by-8 is generally close to 10 feet in length.
Dimensional lumber is the structural element used in the building of almost all types of residential homes. It is used in buildings because of its consistent sizing, allowing builders to use them interchangeably throughout the house.
Dimensional lumber is planed, sawed, and smoothed to make it ready for use. Then, it is standardized throughout the country.
This means that everyone—a DIYer or a builder—uses the same size even after the decrease in dimensions. For example, a 2×8 with an actual measurement of 1 ½ × 7 ¼ will be the same all over the country.
Lumber Dimensions – Nominal Size and Actual Size
All dimensional lumber has nominal and actual dimensions. Dimensional lumber’s nominal dimensions are the dimensions used for selling the lumber.
They are the commercial dimensions, not the actual dimensions of the piece of lumber. Dimensional lumber’s actual dimensions are the dimensions of the finished product after the lumber has undergone processing.
These are the dimensions you get when you measure the lumber you bought from the market with a measuring tape. Due to sawing and additional processing like milling, the actual size of the lumber is less than the nominal size.
So a 2×4 is not 2 inches deep and 4 inches wide. So the processing will reduce the size, and the actual size of the lumber becomes 1 ½ × 3 ½.
The dimension decrease follows a simple rule of thumb. When you know the nominal size of lumber, you can use this rule to determine its actual size.
- For nominal sizes less than 1 inch, reduce ¼ inch to arrive at the actual size.
- For nominal sizes, more than 2 inches and less than 8 inches, reduce ½ inch to get the actual size.
- For nominal sizes, 8 inches and more, subtract ¾ inches to determine the actual size.
Nominal Lumber Sizes
Nominal lumber size is the marketed size. It is a whole number that is easy to remember. However, it is not the true size and exists in name only.
So, although you know that the 2×8 is not the accurate dimension, you will still call it two by eight as it is the “name” or “nickname” of the board.
Actual Lumber Sizes
Now, the reading you record when you measure the board with a tape is the actual size or dimension of the board. It is usually ¼ inch to ¾ inch less than the nominal size.
Rare Case: Nominal And Actual Dimensions Match
You usually won’t find lumber with nominal and actual dimensions that match. As all lumber in the U.S. is standardized, every lumber piece has a standard nominal and actual size.
When you tear down a very old house, you may only encounter lumber with the same nominal and actual dimensions. The wood will feel thicker, and your suspicions will be confirmed when you apply a measuring tape. A 2×8 will truly be a 2 by 8.
However, the standardization of lumber has changed over time. So if you try to reuse the old wood at another house, it will be challenging unless all other areas of the house also use the old variety.
If you try to reuse it for a newer wall that has been built with the current standardization, the old lumber will protrude out of the wall. However, you can mill down the wood to give it the current dimensions or use it for places with the older lumber.
Based On Material
Suppose you’ve ever taken measuring tape to a hardware shop or lumber yard. In that case, you may have observed that not only do the actual and nominal sizes differ, but there is also an inconsistency in the difference.
This is because stores measure and sell hardwood like maple, cherry, and oak differently than they measure and sell softwood like spruce, fir, and pine. Also, they sell hardwood by the board foot, a unit of volume, instead of by board dimensions.
Plywood And Sheet Goods
Most plywood sheets come in dimensions 4×8. Their nominal thickness is usually ½ inch and ¾ inch. However, like other woods, their actual sizes differ from the nominal sizes.
So, the actual measurement of a ½-inch-thick plywood sheet is 15/32 inches, while a ¾-inch thick plywood sheet actually measures 23/32 inches. Also, each face of the plywood is graded.
They are graded A, B, C, or D depending upon the finish, with A being the best with the smoothest sanded finish. So, both sides of A.A. plywood will have A-graded quality, while B.D. Plywood will have a B grade for one side and a D grade for the other.
Hardwood Lumber Lengths
Hardwood lumber is available in lengths 8 feet, 10 feet, 12 feet, 14 feet, going up to 24 feet. An 8-feet-long hardwood will only be ¼ inch shorter since the length can only be reduced by that much.
When buying hardwood lumber, consider the length, width, and thickness. Although the nominal and actual size of the width and thickness differ considerably, the length remains almost the same.
Hardwood Lumber Dimensions
Hardwood lumber is mostly polished and used for furniture and cabinetry. They may have one or more polished surfaces.
The final product sizing will depend on the number of polished surfaces and the standard measurement system for hardwood lumber—the quarter system or the board foot.
As a result, the sizing standard for hardwood lumber is quite confusing. The polishing smoothens the surfaces and removes saw marks if any. The stock may be surfaced (polished) on one side (S1S) or two sides (S2S).
Here are some standard measurements:
|Nominal thickness (in inches)||S1S (in inches)||S2S (in inches)|
When sold according to the quarter system, every quarter refers to ¼ of thickness, so the 7/4 board is around 1-¾ inches thick.
So, if you need a 1-inch thick board for your project, you should get a 5/4 board or 1¼ board (actual size) to allow for the additional ¼ that has been milled down.
A unit of volume, 1 board foot, is equivalent to 144 cubic inches when sold by the board foot. So, a 1 board foot measurement means the board’s thickness is 1 inch, and the length and width are 12 inches each.
Hardwood is often sold in random widths, which you’ll need to size according to the project. So you must consult the lumber supplier or the contractor before finalizing the design and purchase.
Glue-Laminated Lumber Dimensions
Glue-Laminated Lumber Dimensions are available in various widths and lengths and are further customizable. Here too, the nominal and the actual size are a bit different.
The Standard Specification for Structural Glued Laminated Timber of Hardwood Species publication specifies the standard widths and lengths.
Although glue-laminated lumber comes in a wide range of widths and lengths, it can be further customized according to the need. Likewise, the length of each piece is customized. The depth generally ranges from 6 inches to 30 inches.
Some nominal vs actual widths are listed below.
|Nominal width (in inches)||Actual width (in inches)|
|4||25/8 or 7/2|
|6||41/8 or 11/2|
Softwood Lumber Lengths
Softwood lumber lengths exhibit little variation in terms of nominal and actual dimensions. This is because processing has little impact on length, which is essentially unchanged pre-and post-processing.
There is no significant difference between softwood lumber’s nominal and actual length. They come in standard lengths between 6 feet and 24 feet in 2-ft increments (6 ft, 8 ft, 10 ft, and so on, up to 24 ft).
Softwood Lumber Dimensions
Dimension lumber is sawed softwood lumber that is 4 to 12 inches (10.2 to 30.5 centimeters) wide and 2 to 5 inches thick (or 12.7 to 12.7 centimeters).
The Voluntary Product Standard PS 20-20 American Softwood Lumber Document specifies lumber’s nominal and standard sizes.
You may use the rule of thumb stated earlier in the article to arrive at softwood lumber’s actual breadth and width dimensions.
Why Is Dimensional Lumber Smaller In Comparison To Nominal Dimensions?
Dimensional lumber is smaller compared to nominal dimensions because the lumber undergoes processing after being cut to its nominal size. Processes like milling and sawing lead to a reduction in size.
How Far Can A 2×8 Span?
A 2×8 has an actual dimension of 1 ½ × 7¼ or 38 × 184 mm. A 2×8 can span as far as 1.5 × 8 or 12 feet.
How Wide Is A 2×8 Board Actually?
A 2×8 board is actually 1½ × 7¼ wide.
Lumber boards are cut in nominal dimensions. They then go through additional processing. These processes like sawing, milling, and polishing lead to a reduction in size.
So the final product that the customer receives is smaller than the nominal size. A 2×8 lumber has an actual length of 1 ½ × 7 ¼ or 38 × 184 mm after it has undergone all the required processing procedures.
Learn how to store lumber outside safely for your DIY project when you don’t have enough space indoors.