Lumber Dimensions – Weird 2×4 Lengths?

lumber dimensions - strange 2x4 lengths

I love to use 2x4s to build simple projects around the house and garage — projects that call for a little bulk and strength (like workbenches and shelves), but not too much woodworking finesse. Best part about 2x4s is that they’re cheap and easy to find. However, shopping for 2x4s can be a little confusing. That’s because they’re sold in somewhat odd lengths, which at first glance doesn’t seem to make sense.

For example, my local Home Depot store sells 2x4s that measure 92 5/8″, 104 5/8″, and 96″. The different board lengths aren’t really a problem with most projects I build, since I usually have to cut the boards in several pieces anyway. But on a recent shopping trip, I got curious about the odd sizes, and wondered if there might be some advantages in me choosing one length over the other. Before I could answer that question, I had to find out why 2x4s come in different lengths to begin with, and what they’re really used for.

Pre-Cut Stud: 92 5/8”
This is probably the most common 2×4 you’ll see at places like Home Depot. Sometimes called a “pre-cut stud,” it’s a little shorter than a full 8′ board, which makes it perfect for building an 8′ wall (hmm?). Keep in mind that a typical wall has several components that add up to make an 8′ ceiling height (see below).

lumber dimensions 2x4 precut 8-foot ceiling

At the top of the wall are two horizontal 2x4s sandwiched together (called a “double top plate”), and another horizontal 2×4 along the bottom (called a “bottom plate”). In between go the 2×4 studs. To create a wall that will match up with a typical 4×8 sheet of drywall, the studs need to be a little shorter — 92 5/8” to be exact. This also allows a little extra room along the bottom of the wall for variances in flooring and to keep the drywall from soaking up moisture from the floor.

Pre-Cut Studs: 104 5/8″
This 2×4 is made for building walls in rooms with 9’ ceilings. Similar to the construction of an 8’ wall, this stud allows room for a double top plate, single bottom plate, and some extra space along the bottom to compensate for variances in flooring and to protect the drywall from moisture on the floor (see below).

lumber dimensions 2x4 pre-cut stud 9-foot ceiling

2×4 – 8′ Lengths
Although not quite as common as the pre-cut studs I described above, my local Home Depot has a fairly good selection of 2x4s that measure 8 feet (96”). These come in handy for projects where I’m building something around a 4×8 sheet of plywood. With both boards being the same length, I can sometimes save myself a few cuts with the saw (see below).

lumber dimensions 2x4

Which Length Should I Buy?
All of the boards I’ve described above work fine for building smaller projects, since you’ll likely cut the boards into several pieces anyway. The difference you’ll want to look for is price, which can vary significantly from one type of 2×4 to the next, depending on availability and specials your local store might be offering on a particular size board. At times I’ve seen the longer studs (104 5/8”) sell for less than the shorter versions. Shop around and make sure you’re getting the best price per foot.

Less Waste = More Savings
You can also save money by choosing the most efficient board length for the particular project you’re building. For example, some project pieces might yield less waste if they are cut from a 6′ board rather than 8′ board (or vice versa). My free EZ Board Length Calculator does the math for you — helping you choose the most efficient (and economical) boards for your next project.

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