# 2x4 lumber **URL:** \ **Category:** Factual Questions\ **Created:** [August 28, 2001, 8:25pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595 "2001-08-28T20:25:54Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![mudpupper](https://avatars.discourse-cdn.com/v4/letter/m/77aa72/32.png) [@mudpupper](https://boards.straightdope.com/u/mudpupper)\ **Post date:** [August 28, 2001, 8:25pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/1 "2001-08-28T20:25:54Z")
I looking for finish off some parts and of the home I just and haven’t really worked with wood too much. When measuring lumber, why isn’t a 2x4 really 2 inches by 4 inches? ---
**Author:** ![Nen](https://avatars.discourse-cdn.com/v4/letter/n/c5a1d2/32.png) [@Nen](https://boards.straightdope.com/u/Nen)\ **Post date:** [August 28, 2001, 8:29pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/2 "2001-08-28T20:29:14Z")
It is 2" x 4" prior to being milled. In the milling process (making the edges straight) they remove some material. Thus, a 2" x 4" is 1 [sup]3[/sup]/[sub]4[/sub]" x 3 [sup]3[/sup]/[sub]4[/sub]" after milling. ---
**Author:** ![IzzyR](https://avatars.discourse-cdn.com/v4/letter/i/2acd7d/32.png) [@IzzyR](https://boards.straightdope.com/u/IzzyR)\ **Post date:** [August 28, 2001, 8:33pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/3 "2001-08-28T20:33:46Z")
My understanding is that it is due to shrinkage, not milling. By now the size has been standardized, as nen notes. (For larger pieces of wood it gets a half inch smaller than the official measurement, due to more shrinkage). ---
**Author:** ![Nen](https://avatars.discourse-cdn.com/v4/letter/n/c5a1d2/32.png) [@Nen](https://boards.straightdope.com/u/Nen)\ **Post date:** [August 28, 2001, 8:44pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/4 "2001-08-28T20:44:48Z")
> [@](#): > > \*Originally posted by Nen \* > Thus, a 2" x 4" is 1 [sup]3[/sup]/[sub]4[/sub]" x 3 [sup]3[/sup]/[sub]4[/sub]" after milling. Gah! I’m in the damn construction biz and I mess up my facts. Make that 1 [sup]1[/sup]/[sub]2[/sub]" x 3 [sup]1[/sup]/[sub]2[/sub]". ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [August 28, 2001, 8:46pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/5 "2001-08-28T20:46:35Z")
Not shrinkage, milling. If it were shrinkage, than you’d have absolutely no consistency in dimensions. The wood is cut roughly to 2x4’s (which used to be the final dimension), kiln-dried, and then planed down to more precise dimensions. As the trees that they make dimensioned lumber from get younger and thinner, there may be more processing in there to get rid of cupping and warping. Even so, old-timers will snort in disgust as they sort through the piles of lumber in the lumberyards and bitch about how you can’t get good lumber nowadays and how expensive it is. ---
**Author:** ![IzzyR](https://avatars.discourse-cdn.com/v4/letter/i/2acd7d/32.png) [@IzzyR](https://boards.straightdope.com/u/IzzyR)\ **Post date:** [August 28, 2001, 8:47pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/6 "2001-08-28T20:47:20Z")
In that case change my “facts” too. I think a 2 x 10 is 1 1/2 x 9 1/4. ---
**Author:** ![Tedster](https://avatars.discourse-cdn.com/v4/letter/t/4491bb/32.png) [@Tedster](https://boards.straightdope.com/u/Tedster)\ **Post date:** [August 28, 2001, 8:48pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/7 "2001-08-28T20:48:04Z")
It might have been before milling, but I have antique furniture where 1" lumber is, well, 1" I suspect years ago a 2x4 really was 2x4; anybody got the straight dope on this? ---
**Author:** ![Labdad](https://avatars.discourse-cdn.com/v4/letter/l/439d5e/32.png) [@Labdad](https://boards.straightdope.com/u/Labdad)\ **Post date:** [August 28, 2001, 8:53pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/8 "2001-08-28T20:53:05Z")
> [@](#): > > \*Originally posted by Tedster \* > \*\*It might have been before milling, but I have antique furniture where 1" lumber is, well, 1" > > I suspect years ago a 2x4 really was 2x4; anybody got the straight dope on this? \*\* I have owned three houses: the first was built in 1879, the second in 1913 and my present home was built in 1926. The 2x4s in all of these houses are in fact two by four. When the present standard of 1 1/2 x 3 1/2 came into being, I don’t know. ---
**Author:** ![bashere](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@bashere](https://boards.straightdope.com/u/bashere)\ **Post date:** [August 28, 2001, 9:34pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/9 "2001-08-28T21:34:27Z")
> [@](#): > > Even so, old-timers will snort in disgust as they sort through the piles of lumber in the lumberyards and bitch about how you can’t get good lumber nowadays and how expensive it is. Who are you calling an old-timer? I’m 31 and I do that. ---
**Author:** ![DanBlather](https://avatars.discourse-cdn.com/v4/letter/d/f4b2a3/32.png) [@DanBlather](https://boards.straightdope.com/u/DanBlather)\ **Post date:** [August 28, 2001, 9:44pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/10 "2001-08-28T21:44:13Z")
> [@](#): > > \*Originally posted by Tedster \* > **It might have been before milling, but I have antique furniture where 1" lumber is, well, 1"** Wood used for furniture is a whole different story. Generally hardwood is milled by the furniture builder to the dimensions required. In the U.S. the rough wood is available in a variety of sizes in increments of a quarter inch. In the old days, milling was done using hand tools like saws and planes. ---
**Author:** ![Tedster](https://avatars.discourse-cdn.com/v4/letter/t/4491bb/32.png) [@Tedster](https://boards.straightdope.com/u/Tedster)\ **Post date:** [August 28, 2001, 10:11pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/11 "2001-08-28T22:11:13Z")
> [@](#): > > \*Originally posted by DanBlather \* > \*\* > In the old days, milling was done using hand tools like saws and planes. \*\* Maybe, but at least when they advertised a 2"x4" you could count on it being 2"x4" ---
**Author:** ![mmmiiikkkeee](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@mmmiiikkkeee](https://boards.straightdope.com/u/mmmiiikkkeee)\ **Post date:** [August 28, 2001, 11:42pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/12 "2001-08-28T23:42:58Z")
Yes, in the old days a 2x4 was really 2"x4" when you got your hands on it. My parents and grand parents used to run a small saw mill in rural Alberta from about 1940 to 1960. They cut the planks rough to 2 1/2 by 4 1/2, then smoothed them out to 2"x4"; they sold green lumber (not kiln-dried). So up here anyways the “old days” were no more than 40 years ago. You can still get planks that are full-sized, but you probably have to go to the sawmill operator, and pay extra for them. You might also be able to place a special order from a big store, but that would be even more pricey. ---
**Author:** ![johnson](https://avatars.discourse-cdn.com/v4/letter/j/d07c76/32.png) [@johnson](https://boards.straightdope.com/u/johnson)\ **Post date:** [August 29, 2001, 12:21am UTC](https://boards.straightdope.com/t/2x4-lumber/78595/13 "2001-08-29T00:21:52Z")
We have a Sears and Roebuck house from around 1930. The first thing my father-in-law said when he looked in the attic was “Wow–those are real 2x4s.” I’ve wondered, with my replacement cost homeowners insurance, whether I could get real 2x4s replaced. Somehow I kind of doubt it. ---
**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\ **Post date:** [August 29, 2001, 12:43am UTC](https://boards.straightdope.com/t/2x4-lumber/78595/14 "2001-08-29T00:43:08Z")
Can you say “nominal”? Often things are named for convenience not accuracy. Pipes, boats, electrical devices etc. are often named to a round number ---
**Author:** ![Tedster](https://avatars.discourse-cdn.com/v4/letter/t/4491bb/32.png) [@Tedster](https://boards.straightdope.com/u/Tedster)\ **Post date:** [August 29, 2001, 1:35am UTC](https://boards.straightdope.com/t/2x4-lumber/78595/15 "2001-08-29T01:35:22Z")
> [@](#): > > \*Originally posted by sailor \* > \*\*Can you say “nominal”? Often things are named for convenience not accuracy. Pipes, boats, electrical devices etc. are often named to a round number \*\* Exactly! Well, almost. 2"x4" is a nice, round number, and the lumber itself used to reflect that dimension. The name stuck, if the actual dimensions haven’t. “Say, Hank, hand me that one and three-quarter by three and three-quarter” just doesn’t sound right, either. ---
**Author:** ![CrankyAsAnOldMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crankyasanoldman/32/11670_2.png) [@CrankyAsAnOldMan](https://boards.straightdope.com/u/CrankyAsAnOldMan)\ **Post date:** [August 29, 2001, 2:18am UTC](https://boards.straightdope.com/t/2x4-lumber/78595/16 "2001-08-29T02:18:09Z")
First of all, remember that hardwoods sold for furniture making are different than softwoods used for construction. So a maple table leg from back yonder which seems to conform to some standard is sort of like an apple-oranges comparison. As sailor said, 2 x 4 is nominal. The actual measurements as set by the American Softwood Lumber Standard are less. However, even cut green the lumber isn’t 2 X 4. It’s cut to 1 9/16 and 3 9/16 so it will shrink to as it dries does to the appropriate 1 1/2 by 3 1/2 size. Construction lumber used to be milled, marketed, and sold locally, and lumber _grading_ wasn’t standardized in the U.S. until after 1925. Whether that is when sizing also became standardized, I don’t know. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [August 29, 2001, 7:04am UTC](https://boards.straightdope.com/t/2x4-lumber/78595/17 "2001-08-29T07:04:31Z")
> [@](#): > > My understanding is that it is due to shrinkage That’s gonna happen when you expose your wood to cold water. ---
**Author:** ![warmgun](https://avatars.discourse-cdn.com/v4/letter/w/ecccb3/32.png) [@warmgun](https://boards.straightdope.com/u/warmgun)\ **Post date:** [August 29, 2001, 7:25am UTC](https://boards.straightdope.com/t/2x4-lumber/78595/18 "2001-08-29T07:25:02Z")
Old timers can bitch and moan all they want, but when I design and built houses with _rough_ lumber I want it to be straight so that all my drywall, T111, etc will land on the joints. It’s not just the 2x4s that have changed, it’s the other materials as well - and construction tecniques. As well as pre-cut trim, et al. ---
**Author:** ![The\_Great\_Gazoo](https://avatars.discourse-cdn.com/v4/letter/t/67e7ee/32.png) [@The\_Great\_Gazoo](https://boards.straightdope.com/u/The_Great_Gazoo)\ **Post date:** [August 29, 2001, 1:56pm UTC](https://boards.straightdope.com/t/2x4-lumber/78595/19 "2001-08-29T13:56:18Z")
> [@](#): > > \*Originally posted by Little Nemo \* > \*\* > > > [@](#): > > > > My understanding is that it is due to shrinkage > > That’s gonna happen when you expose your wood to cold water. \*\* \ All right, LOL! Good one, Little Nemo! ---
**Author:** ![Neurodoc](https://avatars.discourse-cdn.com/v4/letter/n/848f3c/32.png) [@Neurodoc](https://boards.straightdope.com/u/Neurodoc)\ **Post date:** [August 31, 2001, 8:24am UTC](https://boards.straightdope.com/t/2x4-lumber/78595/20 "2001-08-31T08:24:50Z")
My house was built in 1924. The framing is redwood and all “heartwood.” The “2x4” studs are true 2"x4", and the joists are true “2x8” and “2x10” (for ceiling and floor joists respectively). This “true dimension” lumber is referred to as “rough cut.” Indeed it is not so smooth on its surface as modern lumber. But it looks pretty damned straight to me. I think that the milling process, to produce straight edged lumber, is the reason modern “dimensional” or “nominal” lumber is smaller than so-called “rough cut.” The extra milling is necessary to assure straight pieces because of the low quality of the modern wood. The wood used to make my house 75+ years ago was strong, straight, stable and fine enough “to build a church,” as my grandaddy used to say, without any need for further milling. In other words, I think the reason “2x4s” are not really 2x4s is that most modern lumber sucks compared to what used to be available. You won’t read that in any carpentry texts, but that seems to be the best explanation.