If you’re new to woodworking you have probably noticed when going to start your project that your so called 1×2 is actually a 3/4″x1-1/2″. Confusing, right?! I have made a printable lumber size chart down below for you so you can download and/or print it to hang in your workspace.
Now let’s go over the history of why the actual lumber dimensions are different from the nominal dimensions.
What is the difference between nominal & actual lumber dimensions?
You’re probably wondering why would someone make wood dimensions so confusing? I totally agree but there is a good explanation to this madness.
Nominal Lumber Sizes
Nominal lumber sizes are your common names that we all know like 1×2, 2×4, 1×3. The nominal dimensions are the size of the board before it is ran through the planer, squared to size and kiln dried. That is why the actual size is always smaller than the nominal lumber size we have known to call them.
Actual Lumber Sizes
Next time you’re shopping for wood look at the price sticker on the shelf. You will notice they have two sizes for your boards. The actual lumber size will be stated towards the bottom of the price sticker. That is the size of the board after it has been trimmed, dried and squared off.
The actual lumber dimensions refer to only the width and depth of the board but not the length. Keep in mind that the actual lumber size is anywhere from 1/4 to 3/4 inch smaller than its nominal lumber size. A good rule to keep in mind is:
General Rule To Follow
- 1″ boards = ¾” thick
- 2″-6” boards → subtract ½”
- 8+” boards → subtract ¾”
For example 1″ thick board is going to be 3/4″ thick. A 2″ thick board is going to be 1.5″ thick. And a 8″ thick board is going to be 7.25″ thick.
Why are lumber sizes different than the actual lumber dimensions?
The nominal lumber dimensions are your common board size names like 1×2 and 2×4. When wood is cut down, trimmed to size, squared off and dried out you will always have shrinkage. As the years have gone by our process of creating lumber has gotten more consistent. Making it easier for big box stores to sell lumber that is consistent in size.
Free printable lumber size chart
To make life easier I have created a free printable for you to put in your workshop. If you’re feeling overwhelmed by the craziness of lumber sizes, don’t!! Over time and the longer you pursue woodworking lumber sizes will become second nature. Until then download this printable to have to make the learning process easier.
For more tutorials and guides about getting started with DIY basics and woodworking check out these other articles.