2x2 lumber at Home Depot is now 1.28x1.28. Actual size is supposed to be 1.5

Shouldn't the normal size be 2? Given, well, the name?

You'd think so, but no.
Short story is the 'nominal' size is the size before going into a planer to smooth the faces.
Yes, it makes little sense, like many things related to construction stuff.
- Yeah sorry. The tree was originally 50ft tall so we call the pieces that. But you only get 3ft
  
  Is like buying 1200lbs steaks because that's what the cow weighs before it gets parted
- It's not a 2x4 it's a "2x4."
The two-by-fours at your local home center are not 2 inches thick or 4 inches wide...not anymore at least. They spent several weeks at that size though. The sawmill cut them to that size to stack and kiln dry, and then when removed from the kiln they are then milled straight and square. Used to be they would sell the rough stock to carpenters who would do the milling themselves, but then they figured out that the railroads were charging them a fortune to ship a lot of wood that was going to be ground to sawdust anyway, so they started milling the boards before shipment. Same amount of construction lumber arrives at the construction site and it took less fuel for the locomotive to deliver it.
- they are then milled straight and square
  
  Lol. Trying to find lumber that's straight and square is a pipe dream these days.
Lumber is weird because it has been industry standard to lie about dimensions since before the US existed so it’s just kinda a thing they get to do
- No its not Maybe in the US? At least here, it is and has to be, very precise especially when it comes to industry quality. It is precise down to the mm!
- It's not exactly a lie, just a standard. Nominal board sizes were based on the unfinished lumber size. Another 1/4 inch is taken off each side to get a smooth surface that makes it easier to work with.
  
  Here's an old image (reddit warning)
  
  https://www.reddit.com/media?url=https%3A%2F%2Fexternal-preview.redd.it%2F6Oy1DmXVFs0lyKxq9OmjaI-2gsPj8QO6joLlY1rB7m4.jpg%3Fauto%3Dwebp%26s%3D4fa73a2eaf8d96d4de26378be1ba9c404b210685
  
  that shows the rough cuts of boards from a log. When they look at a log, they determine how many of each size they can get from it, and at that point, a 2x4 is 2 inches by 4 inches.
- Not entirely true. I lived in a house that was just over a century old. The framing was exactly what it said it was, a 2x4 was 2” by 4”. Same for all the structure. These were mill cut, but still pretty clean. It was WW2-ish and after that we started to get planed lumber that gave us 1.5x3.5. It wasn’t even until probably the early part of the 1900s that lumber started to become “dimensional”, as in the standard sizes we know of today.
- How could you use bundle when Business is the collective noun?
As if american measurements have ever made sense. Look up how they measure screws or wires and despair.
- Or shotgun shell sizes and loads.
  
  "It all started in 1840 when the dram was a common unit of measurement..."
- It's a wonder they manage to build anything. They have pocket calculators dedicated to the building industry. It's surreal.
- How do they measure despair?
- The European wire gauge system makes no sense. There I said it. I don't need to know the O.D. of the wire, I need to know the amp rating. The O.D. only becomes an issue for bending radius and there is a chart for that as well. Nothing is stopping some a**hole from making a wire almost completely out of plastic that has the O.D. of a typical 14AWG but can't carry any serious amount of current under the European system. Under the AWG you always know what the current capacity is.
  
  And while we are at it, you might as well standardize your wire sizes based on copper. You are never going to use anything except copper. So your units should reflect the material. I am building a chemical skid, that has nothing to do with the distance between the equator to the north pole.
  
  Also when is the last time you were running wires that you needed a mm of precision? Meanwhile a fraction of an amp really does matter. So should not the thing that does matter be reflected in the product?
The convention is 2" before milling. Milling takes off 1/4"on each side, so the result is 1.5".
- Is this a joke? (I know it isn't).
  
  Why would I want to know the dimensions of the unfinished product? I'm not a construction worker, so honestly is there any reason?
- Why was that ever accepted? I don't care what size it was before milling. If I buy a 2x2 I want a 2x2.
They were when the name was made, but due to changes in the manufacturing process, they aren't anymore. The name stuck, though.

https://www.popsci.com/two-by-four-lumber-measurements-explained/
- So don’t fret. The next bundle of 2-by-4s you pick up in the hardware store are certain to be the exact same size: 1.5-by-3.5 inches.
  
  So they can measure precisely, after all
It's due to the milling to square it.

You can get rough cut 2x4 or 2x2 or anything that are actually that size but by the time you trim and square it you will end up at the measurements sold in big box stores

Edit: I mean the size they used to be in store, not OPs version :(
- I think this commenter is trying to say that the nominal size of a 2x2 is 2" by 2" (and it looks like they typo'd nominal to "normal")
  
  The actual size of a 2x2 is 1.5" by 1.5", and OP incorrectly calls these dimensions nominal
It was done for largely sensible reasons.

https://youtu.be/WaJFudED5FQ?si=7j005FmfJVr_JQL_

In short, a 2x4 was originally 2x4 inches, full stop, but it was found that this size wasn't necessary for the strength being applied to them in construction. We were wasting lumber for no reason. They went through a few cycles of sizing down as the actual needed strength was understood better. The naming convention stuck, though.
- Here is an alternative Piped link(s):
  
  https://piped.video/WaJFudED5FQ?si=7j005FmfJVr_JQL
  
  Piped is a privacy-respecting open-source alternative frontend to YouTube.
  
  I'm open-source; check me out at GitHub.
No.

https://www.lowes.com/n/how-to/nominal-actual-lumber-sizes
It's weird because it's the size of lumber BEFORE smoothing the edges. Manufacturers take this inch a mile and the 2x4 (as well as all other dimensional lumber) has gotten smaller and smaller.
O that’s the size before planing.
Even if it was 2" from the lumber yard, it would shrink or expand quite a bit depending on the moisture content. Expecting natural products to be an exact size would be crazy, especially when talking about construction lumber.

Now this is a very extreme case, but it was probably milled to 1.5" soaking wet, and shrank a bunch after drying out on the rack. That's also a big reason why they're all warped.

Is nobody gonna call out OP for wearing socks with sandals? ...and, ostensibly, while preparing to do carpentry?!?

That's like a cardinal sin squared!

Jesus did it
- Not in socks
Nah nothing wrong with wearing socks with sandals when you’re home. Do what ever the hell you want.

But I do agree with wearing proper footwear while doing dangerous things.
- Oh absolutely. I wear socks with sandals because my soles sweat and make my sandals sticky.
  
  But yeah, wear proper attire for the work you do!
Can't you see those are safety sandals. And just like safety squints, are approved PPE across the whole 3rd world industrial sphere. OP will be perfectly safe.
- Nope. Definitely dead.
At least the socks aren't white.
I regularly wear socks and sandals along with shorts and a sweater.

There was also a time I went to lunch with that plus a lab coat and hairnet.
- Sounds like a Rick and Morty episode.
I don't condone it, but I've done something similar once in a Boy Scouts meeting as a scout. Had sandals on and I don't remember the full meeting, but at one point we were chopping wood with an axe. I did it, but that's not my brightest move. There was also a time where I was getting my metalworking badge and entered the forge one time for a kinda free time work on your project thing with shorts on by mistake. Nobody stopped me in either case. This wasn't pre-2000s, so I'm not sure how I got away with either event considering safety is usually taken much more seriously nowadays.
My COVID home-improvement project was hardwoods. Something like 1000sqft. Never did it before. Did 90% of it wearing no more than basketball shorts and flipflops. W/e. Only a few toe injuries.
- Well if it was only a few. /s
don't forget the unbranded Chinesium calipers.

Mitutoyo or bust.
- For a machinist yep. For home gamers, a waste of money. They don't have the knowledge of where and when to use them nor the skills to get accurate repeatable measurements. So for OP's use whatever CCC, (Cheap, Cheerful, Chinese), caliper he's got is good enough.
  
  It's the definition of "nominal size is what ever we say it is" that pisses me off. Buying wood/lumber is the worst offender of Nominal sizing, but even metals are getting worse. I used to buy a round bar of say, ASA1018 and it would be +0"/-.002". It's now +0/-.006", (that's +0/-.05mm and +0/-.15mm for those living in Boca Raton). At the end of my career as a toolmaker I was often forced to purchase oversized stock and waste time turning said stock into the actual sizes required.
- My toolbag calipers are cheap hardware store ones. They're accurate enough and I'm not out much when they inevitably get damaged or lost.
- I can accept the poor quality tools that might be off by a few hundredths, but using imperial on precision measurement devices is unforgivable.

Um, wait. I would think that violates some sort of law (but I guess maybe we haven't codified this?). I mean, building plans expect standards in materials, right? So how can a building meet codes if the materials are not within the expected specs?

Agreed, seems like some kind of weights and measures violation.
I'm going to guess they can get away with this because 2x2s aren't intended for structural use. I've never built one into a floor, wall or ceiling.
- Used for furring strips everywhere. Line a block wall with them and sheet it for example.
- Sounds like the situation here... good call
It's probably 2x2PT or something. There are standards for board widths.
The 2x4s that have been sized this way do meet structural code. It was found that a full 2x4 is way over spec'd for what they were used for, so why bother wasting extra parts of the tree?

Pretty much everything built with dimensional lumber in the last century has been done with undersized 2x4s, and it's fine. The name stuck for historical reasons. Companies that build houses and order this stuff by the pallet all know what the real size is, and so do building inspectors.
- Rough 2x4s were 2" x 4". Then we started finishing them for better consistency, taking about 0.5" from each dimension. Later we started using saws with narrower kerfs to have less loss due to saw blade width, better cutting and planing systems so the rough size could be smaller and still have the same finished size, then they lowered finished size some more.
- These are even smaller than that. A standard 2x4 is 1.5x3.5.
- Thanks for the explainer.
- Pretty much everything built with dimensional lumber in the last century has been done with undersized 2x4s, and it’s fine.
  
  It's fine, folks. Nothing to see here.
You simply change the expected specs.......

2x2PT has been 1.25x1.25 for as long as I can remember (10 years or more). It's only the pressure treated deck stuff for railings. This does not apply to the rest of the 2x lumber, as those are still 1.5 actual. I got Simpson corner 2x2 brackets for crazy cheap way back but ended up not really using them. The 2x2s are warped to hell and a ripped 2x4 was too big in the original 2x dimension.

I'm wondering if it's a regional thing? I just looked online for pressure treated 2x2's and all the ones I'm seeing (home hardware, home depot, advantage lumber, etc) list as actual being 1.5x1.5
- That's possible. I just moved from CA to MI 2 years ago. I know they were 1.5 then because I built alot of props and temp walls with it. I was reusing a 3d printed joint I designed to make a garden trellis when I noticed the wood didnt fit like before.

Why is 2x2 meant to be 1.5x1.5 and not 2x2?

Premill size vs sale size. Something like that. Probably not the correct term.

Similar to how steak is measures in precooked weights.
2x4 is the rough cut dimensions from the sawmill. They end up smaller after drying (wood can hold a lot of water) and planing.
*Planed/straight wood versus raw lumber. It threw me off when I first started building stuff and summed that a 2x4 was actually 2"x4" in all my measurements/plans

*Or it would be straight if you're lucky and don't pick from the top of the bin at Home Depot
The old * uncooked weight

TBH that looks like a furring strip, not dimensional lumber

It's possible they stocked the wrong thing, but it was rung up as Pressure-Treated so maybe they applied the wrong barcode?
- That green tint means it is pressure treated. Just take it back (this time bring a tape measure.)
He probably bought "five quarters"

It's still a bit small, but pressure treated being a little smaller than framing lumber is not necessarily a secret:

https://www.lowes.com/pd/Severe-Weather-Common-2-in-x-2-in-x-8-ft-Actual-1-3125-in-x-1-3125-in-x-8-ft-1-Treated-Lumber/4764128

I appreciate you covering your open toes, safety socks so you’re compliant.

This was pre-job time :) Testing a 3d printed joint with it when I noticed the wood was very undersized.

How is it in countries using the metric system ?
in France :
https://www.mara-materiaux.com/bois-de-charpente/8094-lambourde-38x63-mm-long4-m-traite-9202001090740.html

LAMBOURDE 38x63 mm long.4 M TRAITE Unité de vente : le mètre linéaire 1.42 € /m
5.68 € /(4 m)

So, this is aprox ($6.?) for one "...2x3x(~13ft)..."
(treated wood)
... verry expensive, yet, upfront size disclosure.

Pretty much all of Europe lists wood in exact size of the cut that you get. It sounds highly illegal to call it a 5x5cm piece of wood and sell some other random smaller size.
- Thank God freedom units give us the liberty of doing away with that commie nonsense.

Nothing is immune to shrinkflation aka merchant gouging

What is your definition of gouging
- Highly relevant when topically adjacent to woodworking.
- Increasing prices just to fill corporate pockets, or keeping prices elevated far beyond the market necessity
This has nothing to do with shrinkflation. Just an oddity of the US lumber sizing.

Looks oversized to me, that's 3.25 cm x 3.25 cm, looks like they could take it down by 40% and still call it a 2x2 😇

Is their entire stock like this every time, or just this one batch?

Entire stock as of 5/6/24. I didnt even notice it was smaller than usual, busy trying to find the only-slightly warped boards.
- Good lumber these days is becoming hard to find. I think it is mostly due to the lumber companies trying to pump out a ton of lumber to meet demand.
- 5/6/24
  
  Do you live in future? Today is 08.05.24.

Good thing you checked, that’s ridiculous. If I’d cut a dado for some mixed stock and found out some of them were 1 & 1/3 instead of 1 & 1/2, I’d be pissed.

For a dado, you'd better measure every board.

But in reality, if you're looking for a perfect fit for construction lumber, you'd also better let it dry out for a week before measuring and fitting, cause it was probably 1.5" soaking wet from the yard, and shrank a bunch.
Well, if your dadoing your probably not using soft wood dimensional lumber….
- I’ve found some applications for it, honestly.
  
  I made a work bench with oak 4x4s for legs and dado’d in pine 2x4s for the cross braces. Nice and sturdy with a good enough fit and no movement I noticed over the past 3 years.
There is a lot of manufacturing deviation with lumber. If you are that picky maybe you could try talking to one of the associates. They tend to know the best places to look and they may even help you measure.
- I worked construction in the early 2000s and there was no variation in lumber dimensions.
- Dimensional lumber has negligible variance in width/depth most of the time which is why it's called that. It's really the length that's a crapshoot. Gotta love when you buy a bunch of 10' planks and a couple are a few inches short

Fire Walk with Me - 2x4s (Deleted scene)

Top comment, this. This is gonna be my default when folks ask about dimensional lumber sizes in the future
Beat me to it!

RIP Jack Nance and Ed Wright.
Here is an alternative Piped link(s):

Fire Walk with Me - 2x4s (Deleted scene)

Piped is a privacy-respecting open-source alternative frontend to YouTube.

I'm open-source; check me out at GitHub.

Well shit. That explains alot

There is quite a lot of deviation with lumber these days. If you need something the right size go for a higher quality and then measure them until you find the one you are looking for.