Actual Lumber Dimensions:


Actual Lumber Dimensions:

a beginning DIYer’s handy guide to understanding the actual size of boards

Nothing ruins a set of DIY plans more quickly than not accounting for the actual size of the boards you’re using. Go ahead and laugh at me, but when I was first beginning to build things, I thought a 2 x 4 was actually 2” by 4.” If you’re new to building things, this may be news to you, but the nominal lumber dimensions (the name by which they’re sold and commonly called, ex- 2 x 4, 1 x 4, etc.) is not the same as the actual lumber dimensions.

If you’re a simple soul like me, you’re probably asking why the hell anyone would play such a mean prank on the world. Isn’t calling a board a 2 x 4 when its actually not that size like calling a cauliflower-crusted, marinara and cheese-topped oven disaster a pizza? (Side note: we all know that’s not really a pizza and anyone who tries to invite me over for “pizza” and then proceeds to serve me that cauliflower-cheese-Frankenstein mess will never be a real friend of mine.) So why do they do it?

Historically, when boards were cut and milled to be used for lumber, they were cut at 2” by 4.” By the time they underwent the drying and planing process, they came out to be 1 ½ by 3 ½.” Today’s harvesting and milling processes have changed, but the lumber dimensions still come out to those old standard sizes we’ve all become accustomed to.

It’s a lot to keep track of, so I made this handy lumber chart to help me keep track of my sizes. I refer to this chart when I’m sketching out plans for projects, and hopefully, it’ll help you too.

Actual Lumber Dimensions Chart

Nominal size

Actual size

1 x 2 ¾ x 1½”
1 x 3 ¾ x 2½”
1 x 4 ¾ x 3½”
1 x 6 ¾ x 5½”
1 x 8 ¾ x 7¼”
1 x 10 ¾ x 9¼”
1 x 12 ¾ x 11¼”
2 x 2 1½” x 1½”
2 x 3 1½” x 2½”
2 x 4 1½” x 3½”
2 x 6 1½” x 5½”
2 x 8 1½” x 7¼”
2 x 10 1½” x 9¼”
2 x 12 1½” x 11¼”
4 x 4 3½” x 3½”
4 x 6 3½” x 5½”
4 x 8 3½ x 7¼”
6 x 6 5½ x 5½”
8 x 8 7¼ x 7¼”

Now, mathematics is not my spiritual gifting. You want help picking out a rug or putting together a mean peanut and butter sandwich? I’m your gal (the secret is to add pretzels and banana slices. You’re welcome). You need help with long division? Hard pass. I like to keep this table handy when I’m in the planning stages for my projects so I can make sure I’m calculating everything correctly (on my calculator, of course, not in my head like some genius).

I hope this helps!

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