Jointer vs Planer: What Each Does and Why You Might Need Both

Jointers and planers get confused for each other constantly, and it’s an understandable mix-up because they’re both machines that flatten wood. But they do different jobs, and understanding the difference is the key to milling rough lumber into flat, square, consistent boards. Here’s what each one does, why woodworkers often own both, and how to think about buying them.

What a jointer does

A jointer flattens one face of a board and squares an edge to that face. You run a board across the jointer’s bed and over the cutterhead, and it shaves the high spots until that face is truly flat. Then you stand the board on that flat face and run an edge across to make it square.

What a jointer does not do is make a board a consistent thickness. It flattens one face at a time, referencing whatever surface is against the bed and fence. So a jointer gives you a flat face and a square edge, but the board can still be thicker in some spots than others.

What a planer does

A planer makes a board a consistent thickness with two parallel faces. You feed a board in, and the planer references the bottom face while the cutterhead shaves the top to a set thickness. Run it through a few times, lowering the cutterhead each pass, and you get a board that’s the same thickness end to end.

Here’s the catch that trips people up. A planer references the bottom face, so whatever shape that bottom face has, the top will end up parallel to it. Feed in a board with a cupped or twisted bottom, and you get a cupped or twisted board that’s now a consistent thickness but still not flat. The planer makes faces parallel; it doesn’t make them flat.

Why they work together

Now the relationship makes sense. The jointer flattens one face. The planer then makes the opposite face parallel to that flat face, bringing the board to consistent thickness. Together they turn rough, cupped, twisted lumber into flat, square, consistent stock.

The usual sequence is: joint one face flat, joint one edge square, then run the board through the planer to bring it to final thickness with both faces flat and parallel. That’s the full milling process, and it’s why serious woodworkers who buy rough lumber tend to own both tools.

If you’re buying rough-sawn lumber and want flat, square, consistent boards, you really do want both tools. They each do half the job, and neither one fully replaces the other. The jointer flattens, the planer makes parallel and consistent. Skipping one leaves a gap in the process.

What if you only own one

Plenty of woodworkers start with just one, so here’s the honest picture of each path.

If you own only a planer, you can still bring boards to consistent thickness, but you can’t flatten a cupped or twisted face first. There are workarounds, like building a planer sled that holds a board steady so the planer can flatten the top face, and it works but adds setup and fuss. Many hobbyists start here because good benchtop planers are affordable and capable.

If you own only a jointer, you can flatten a face and square an edge, but you can’t reliably bring a board to consistent thickness, since a jointer references a different surface each pass. This is the less common starting point, because thickness consistency is harder to work around than flattening is.

And if you buy already-surfaced lumber, sometimes sold as S4S, meaning surfaced on four sides, you may not need either tool right away, because the milling is done for you. You pay more for the lumber and give up some control, but it’s a legitimate path, especially when starting out.

How to decide where to start

Think about what lumber you buy and what you’re willing to work around. If you buy rough lumber and want the full milling process, plan for both tools, and know that many woodworkers buy a planer first because the benchtop models are affordable and a planer sled covers flattening in the meantime. If you buy surfaced lumber, you can delay both purchases until your work demands the control they offer.

When you’re ready to look at actual machines, browse the jointer database and the planer database, where you can filter by tier and sort by price to find the ones that fit your shop and budget. If you’re weighing how much to spend, the tools follow the same tier logic as the rest of the site, explained in the how tiers work guide.