Here's everything you need to know about 2x4 lumber! What are the actual dimensions of a 2x4, the best saw to cut 2 by 4 wood, what screws to use in a 2x4 and project ideas to get you started!
2x4 studs are one of the cheapest and easiest sources of lumber for beginning woodworkers. But if you've never built anything before, there's a lot to learn! In this guide, I'll answer all your questions about the humble 2x4 and help you get started on your next project!
What are the actual dimensions of a 2x4?
Believe it or not, a 2x4 board does NOT measure 2" x 4"! The actual dimensions of a 2x4 are 1 1/2" thick and 3 1/2" wide. What?!? Why is a 2x4 not 2" x 4"?
Actual size vs nominal size
2x4 lumber is made from a variety of softwood species. Back in the day, each mill cut down their logs into boards that were roughly 2" x 4" (the nominal size) but the surfacing and drying process was different at each location, resulting in an assortment of actual finished sizes.
Over time, the size of a 2x4 shrunk in order to compete with other building materials. Mills were trying to get more boards out of a single log, and charge the same price. Eventually, the actual size of a 2x4 was standardized at 1 1/2" x 3 1/2" to keep the dimensions consistent throughout the industry.
Standard 2x4 length
2x4 studs are typically 8 feet long, to match the standard length of a sheet of plywood or drywall. You can also find 2x4 studs that are 92 5/8" long, which allows builders to account for the thickness of the boards that run along the top and bottom of the wall.
Pay attention to the lengths listed on the lumber bin when buying 2x4s for a project! My woodworking plans always call for 96" long boards, and grabbing the wrong size may mean an extra trip to the store for more supplies!
In addition to the standard 8 foot length, you can also find 2x4 boards in 10, 12, 14 or even 16 foot sizes. But these are almost impossible to transport home in my car, so I stick with what fits in my small SUV!
What to look for at the lumber yard
Venturing into a lumber yard or the lumber section of the home improvement store for the first time can be daunting! There are so many stacks to choose from! Just grab a lumber cart and wander until you've found the 2x4s you're looking for.
Avoid cracked and damaged boards
When you finally find the pile of 2x4s, you'll probably see a bunch of cracked and damaged boards right on top. These bins get picked through all the time, and the worst ones are left behind. Don't grab boards right off the top!
Dig down or back a few layers until you see all the tightly packed 2x4s all neatly arranged in stacks. These are the boards that haven't been picked over, and there's bound to be some great ones in there! Sometimes there will be a band around a new shipment of lumber, and I'll use my car keys to cut the band and pull out all the good stuff.
Set aside any 2x4 lumber without cracks, missing chunks and deep scratches. I'm usually pretty picky and will avoid as many knots as possible to save myself some work later on.
Look for bowing and cupping
2x4 lumber is cut and milled quickly, and usually isn't given a lot of time to dry. As a result, the boards you find at the store can be cupped and bowed. This isn't a deal-breaker in construction, but a straight board is absolutely necessary for building furniture!
Take a quick look at each board you picked out. Set one end down on the floor, and bring the other end up to your eye. Sight down the length of the 2x4 to see if it's straight. You can usually tell right away if it's curving off to the side. I've seen some that would make a great canoe! 😉
You should also look at the ends to see if the corners are 90 degrees and straight. If it's shaped like a potato chip, it's cupping! This is more common in wider boards, but it doesn't hurt to check.
Once you have the best 2x4 lumber picked out, you can get it cut down into shorter lengths at the store to make it easier to get it home. It can be tricky to fit 8 foot boards into a compact car, and not everyone has seats that fold completely flat like this! 😉
How to cut a 2x4
You can use pretty much any saw to cut a 2x4, but some will do a better job than others. First, let's talk about the two different types of cuts you can make.
Types of cuts
A cross cut severs the fibers across the grain, making the 2x4 board shorter. This is the most common type of cut, and can be made with most saws.
A rip cut slices down the length of the board with the grain. This makes a thinner board, and is commonly used to take off the rounded corners of standard 2x4 lumber. It's difficult to make a rip cut with anything other than a table saw, although it's possible to do it with a circular saw with the right support.
How to cut a 2x4 without power tools
If you want to cut a 2x4 without power tools, try a miter box with a hand saw. The slots in the box will help guide the saw to create a straight cut while you pull the teeth back and forth across the board. You can learn more about how to use a miter box here!
How to cut a 2x4 with a circular saw
Most homeowners have a circular saw gathering dust in their garage (or if you're like me, you store it on this handy circular saw rack!)
It's pretty easy to make a straight cut across a 2x4 with a circular saw just by lining up the blade with the cut line. Holding a speed square next to the base plate will help guide the saw straight. You can also use a jigsaw to cut a 2x4 the same way!
But for the most precise cuts, I recommend making a circular saw jig that you can clamp to the board right where you want it. You can even make rip cuts with this type of jig, so long as the saw is supported properly and doesn't tip.
How to cut a 2x4 with a miter saw
The easiest way to cut a 2x4 is with a miter saw. It can make straight cross cuts as well as angled cuts just by adjusting the blade. If you set up a stop block system, you can create a stack of identical 2x4 pieces in minutes!
The miter saw is perfect for making cross cuts, but it's not safe for making rip cuts. Your fingers will be way too close to the spinning blade for comfort. You can learn all about how to use a miter saw in this guide!
How to cut a 2x4 with a table saw
A table saw can make both cross cuts and rip cuts with ease. I usually use the table saw to trim off those rounded corners on the 2x4, or cut it down into two 2x2 boards.
To make a cross cut on the table saw, you'll need to use the miter gauge or a cross cut sled. A fancy crosscut sled like this one will allow you to make angled cuts easily. I built my table saw stand to accommodate this larger sled on my jobsite table saw!
What size screws to use with 2x4 lumber
The most common screw to use with 2x4 lumber is a #9 or #10 screw that is 2 1/2" long. A #9 or #10 screw is strong enough to hold 2x4 boards together without snapping under pressure. The length will allow the screw to pass completely through the first board and most of the way through the second, without popping out the other side.
Predrilling a hole in your board will prevent the wood from splitting or cracking when you drive in the screw. If you want the screw head to sit below the surface of the wood, drill a countersink hole and use flat head screws. You can learn more about predrilling and countersink screws here.
If you're using pocket hole joinery, you'll need to use 2 1/2" Kreg screws for 2x4s. As you can see in this cut, the 2 1/2" Kreg screw will sit in the pocket at the correct angle to join two 2x4s together at right angles. You can learn more about how to use a Kreg Jig here!
2x4 project ideas
Now that you know how to select, cut and screw a 2x4, you're ready for your first project! I have a bunch of 2x4 project ideas to get you started!
I've built a LOT of 2x4 shelving over the years. They're super strong and can support a lot of weight, plus they're really easy to build with just 2x4s and plywood! These storage shelves are in our shed, and hold all our camping gear, Christmas decorations and more!
You can alter the plans of this simple DIY 2x4 bench to fit any space, or even put it outside!
2x4 patio furniture
Then I added this DIY outdoor end table, with a built in ice bucket to keep drinks cold!
Even this outdoor coffee table is made with 2x4s!
Once you have a few woodworking projects under your belt, you're going to want to build this 2x4 workbench to make your new hobby easier! It comes in handy as a miter saw station too.
So what are you waiting for? Get out to your local lumber yard or home improvement store and pick up some 2x4 boards for your next project today!