Key Takeaways
If you’re shopping for a decking or woodworking project, these few tips can help.
- The lumber that you buy at the store is sold with a nominal size, which is different than the actual size. A nominal size is the original measurement before the lumber is dried — causing shrinkage — and planed to make it smooth. For example, a nominal 2 x 4 measurement is actually 1-1/2 inches by 3-1/2 inches. This is important to note if you have a project that requires specific measurements
- Softwoods (e.g., pine, fir, hemlock, spruce) are sold with measurements that include the thickness and width.
- Hardwoods (e.g., hickory, oak, walnut, cherry, birch) are typically sold with a measurement that only includes the thickness.
Nominal and Actual Lumber Sizes
When you’re shopping for wood for a project, dimensional lumber sizes can get a little confusing. The numbers given for the size of a piece of lumber at the store are nominal measurements. These numbers indicate the size the wood was originally cut to. Before it’s ready to be sold, dimensional lumber is dried and then planed to make it smooth. Wood shrinks as it dries and the planing or surfacing process removes some of the original material. This in turn causes the wood’s actual measurements to differ from the nominal measurements. If your project requires specific measurements, it’s important to check what the actual measurements of your lumber are before you buy it.
Understanding and Identifying Dimensions
The typical nominal dimensions for wood, such as 2 x 4, refer to the thickness and the width of the wood. If a third number is added onto the nominal dimensions, such as 2 x 4 x 96, it indicates the length of the wood.
Hardwood and Softwood Measurements
Different types of wood are sold according to different types of measurements. Softwoods, such as pine, fir, hemlock or spruce, have nominal dimensions that include the thickness and the width.
You may see hardwoods, such as hickory, oak, walnut, cherry or birch, with nominal dimensions that only include thickness. Hardwoods can be surfaced either on one side (S1S) or on two sides (S2S), which will further affect the dimensions. Additionally, hardwoods are sold by volume units, called board feet, rather than board dimensions. A board foot is calculated by multiplying the nominal thickness, width and length of the cut of wood.
Let's Get Started
If you’re ready to start your project, you can order your lumber online and have it delivered to your door. Still have questions? Head to your local Lowe’s, and a Red Vest associate will be happy to help. For help from home or on the go, use Mylow — our AI shopping assistant — to get answers to your home improvement questions.
Frequently Asked Questions
Why Isn’t a 2 × 4 Actually 2 Inches by 4 Inches?
The listed 2 x 4 measurement is the nominal size. These are the dimensions when the lumber was first cut at the mill.
After the lumber is cut, it’s dried and planed smooth. When it dries, it shrinks, so the overall dimensions reduce. Lumber that was originally 2 inches by 4 inches will be 1-½ inches by 3-½ inches after processing.
What Are the Standard Lumber Sizes Available?
Dimensional lumber is used for general construction and framing. These boards are usually sold in standard lengths of 8, 10, 12, 14 and 16 feet.
The most common nominal sizes include:
- 2 × 4
- 2 × 6
- 2 × 8
- 2 × 10
- 2 × 12
What do the numbers in 2 x 4 x 96 mean?
They indicate thickness (2 inches) by width (4 inches) by length (96 inches).