Talk:3138: Dimensional Lumber Tape Measure

I was under the impression this was actually a thing that exists, somewhere. (Separate and apart from so-called "shrink rules" used by patternmakers who create patterns for metal castings). No? JohnHawkinson (talk) 00:36, 6 September 2025 (UTC)

https://www.inchcalculator.com/actual-size-of-dimensional-lumber/ for reference --- MEL

Wikipedia has a similar table. Interestingly, if the values on this table are correct, the xkcd measure fails for the 8 x 8 board. 2605:59C8:160:DB08:988B:772A:4E5:B209 02:18, 6 September 2025 (UTC)

>the xkcd measure fails for the 8 x 8 board Studs and joists are repetitive structure and should be the same as their neighbors. 8x8 are non-routine; even in say a heavy mill building 8x8s are costly enough for the carpenter to measure or trim every column. --PRR (talk) 17:10, 8 September 2025 (UTC)

My house has near full-size 2x4s and 2x6. Very-dry trees were sawn on site, the saw set for 2.0" centers. Band saw has very narrow kerf. About 1.9". A profitable saw-mill would use a coarser blade and push the size down as much as customers would accept (and even a junior carpenter can tell an undersize stud by feel). But here they were clearing land as much as saving money. --PRR (talk) 17:10, 8 September 2025 (UTC)

"I was under the impression this was actually a thing that exists, somewhere" - if doesn't exist now, it soon will. 70.115.234.146 03:59, 6 September 2025 (UTC)

Thinking that there might be a typo in the comic - It says : A "1x8" IS "3/4 BY 7 1/8", yet it should be "3/4 BY 7 1/4".

I no longer want to be a lumberjack! 2A02:2455:1960:4000:748F:2291:F005:1989 06:57, 6 September 2025 (UTC)

I'm a lumberjack and I'm OK. I sleep all night and I work all day! ;-) --Kynde (talk) 05:31, 8 September 2025 (UTC)

This reminds me of when I changed my friend’s text replacements to be slightly misspelled whenever she tried to type a common word in college. She was getting a degree in linguistics and it was SO FUNNY 《プロキシ》(XKCD中毒者) 13:29, 6 September 2025 (UTC)

She should have claimed that she was undertaking "applied linguistics" and investigating how to create a deliberate language change! 92.17.62.87 20:23, 6 September 2025 (UTC)

I was told (and maybe this is wrong), that the dimensions are intended to represent the final thickness of a wall when drywall (usually 0.5" thick) is attached to the studs. Shamino (talk) 20:58, 6 September 2025 (UTC)

I think that's just a convenient side effect. Of course, if the drywall is 1/2 thick, a wall with 2x4 studs will be 4.5 inch thick. RegularSizedGuy (talk) 22:22, 6 September 2025 (UTC)

That would be pretty ahistorical, so I think it is indeed wrong. Drywall is a relatively modern invention, and I think the standardization of 2x4s as 1.5″ thick predates it (need to check that…but even if it didn't, then it would be worse). Wood lath and plaster walls are more like 5/8″ from the stud face, if not more. And, of course, in modern American multifamily residential construction 5/8″ walls are more common, or even double-5/8″ walls (making 1 1/4″) in fire-rated assemblies. So it does not even end up being "convenient," not that a 4" wall assembly is particulary more "convenient" than a 4.5″ or a 4.125″ or a 4.75″ wall assembly…very little turns on the thickness of the stud plus wallboard, but a lot turns on the thickness of the stud cavity (insulation, space for utilities, &c.) or the thickness of the drywall (spacing of electrical outlets, mudrings, etc.). JohnHawkinson (talk) 04:20, 7 September 2025 (UTC)

Once again, the UK wins on ridiculousness. I bought some fencing materials yesterday. The panels were 1.83m x 1.22m, so they could be metric but nevertheless 6' x 4'. I got some presawn posts that were 2400mm long (so kind of 8', or close enough), and they were sold as 75mm x 75mm, so they were 3x3, but they fit perfectly into the 70mm x 70mm post supports I got to go with them. Using metric to sidestep the need for traditional-measurement nonsense...but just keeping the nonsense and throwing new numbers at it. Actually, that should rendered into Latin and put on a scroll as part of a national coat of arms. Yorkshire Pudding (talk) 09:49, 7 September 2025 (UTC)

Since the tape measure uses variable length inches, the watch (provided by the cartoonist) might be similar to Vetinari's clock. (Where individual ticks are of random duration.) I looked to see if xkcd had covered such a clock before (for possible link), but didn't find one. 2600:387:4:803:0:0:0:90 19:16, 7 September 2025 (UTC)

As an aside, I am always bemused about Americans being so stuck on imperial measurements when metric is so much easier. Oh except money...Americans are happy with metric money :o). 59.101.181.77 20:42, 7 September 2025 (UTC)

Oh, undoubtedly. It's literally just counting. The system we all use for enumerating everything (including feet and inches, or furlongs and chains, or drachms and scruples, or whatever else) is base 10. So just use base 10 and give names to 1,10,100,1000, etc. of length/capacity/mass/etc. units, and nobody needs to know anything beyond counting to deal with absolutely everything. Anybody who says pounds and ounces, or yards and miles (or whatever) is superior is objectively wrong.

But.

People get used to things.

So you get the mess I mentioned above.

Adopt the metric system, but then sell milk in 568ml bottles, because that's a pint, and milk inherently belongs in pints, so people have to have that much milk as a unit. Sell syrup and treacle in 454g and 907g cans, so 1lb and 2lb cans of sugary stuff can still exist. Nobody would be able to cope with 400g, 450g, 500g, 900g or 1kg! Keep selling beer and cider in pints, but change spirits to 25ml or 35ml (which you choose is up to you as a licensed bar) from 1/6 of a gill (or 1/5 of a gill in Scotland). Sell fuel in litres, but advertise vehicle fuel consumption in miles per gallon. Yorkshire Pudding (talk) 22:59, 7 September 2025 (UTC)

I know, obviously not the full shilling! 92.17.62.87 23:16, 7 September 2025 (UTC)

I will venture the hypothesis that folk in this conversation are not cooks. It's in the kitchen that the difficulties with the metric system are most frequently encountered. Many Imperial measures are factors of two; it's easy and intuitive to double something or halve something and have the result make sense, as several kitchen veterans have told me over the years, with varying degrees of irritation. A pound (16 ounces), half a pound (8), a quarter pound (4), yada. Too many halvings in the metric system, and you're into fussy decimals. Moreover, if the recipe calls for a pound of butter, and you feed it half a kilogram, thinking that's the metric equivalent and close enough, the biscuits/cookies ain't gonna come out the same, and folk are gonna come after you. I learned years ago to check the cup measure carefully to see if it was graded in ounces or milliliters, and whether the recipe it was supposed to be serving came from Yankeeland or Godzone. Or else. The metric system may be logically superior, but may not be practically superior in all contexts. It might be well to seek reasons, other than the usual dismissive ones, for why, for example, Canada took 15 years to fail to fully convert to the metric system.2605:59C8:160:DB08:F102:9332:DCBD:89C6 03:10, 8 September 2025 (UTC)

I very much am a cook, and that is, I'm afraid, nonsense. Cooking is the perfect example of why metric is better! A recipe written in imperial, or the almost-identical US Customary Units, doesn't work if you substitute a round number of grams in for it, no. Obviously. But that presupposes that recipes naturally occur in imperial, with conversion being necessary if grams are used. Plenty of recipes exist natively in metric though, and are a clumsy mess if performed in avoirdupois.

And "fussy" decimals aren't a problem. If you need to halve 325ml (for example), no recipe will be affected by your using 163ml instead of 162.5 – much as fluid ounce measurements aren't accurate to the half millilitre, millilitres don't need to be either. Being a Brit, I learned to bake bread in imperial because we're across two systems here, and were even more so when I was young, but I forced myself to change, because metric is, inarguably, vastly superior. Working with percentages of hydration when you're in fluid ounces of water and pounds of flour (or the entirely nonsensical volumetric cup system) is utterly ridiculous when you could just use numbers that are exactly equivalent to each other. 1kg of flour, at a 66% hydration ratio? Why, that'll be 660ml of water, which can simply be weighed into the bowl at 660g. Can pounds, ounces, pints, fluid ounces and cups do that? Very much no.

And your halveable measures are all well and good...if you're halving those particular numbers. Anyone can think of numbers that are easily halved though. But what if it's a 2 egg recipe with 3oz of flour, and you want to make 3 eggs' worth? Well, then you need 4.5oz of flour. A bit...fussy, no? Imperial and US-measure recipes feel like examples of pounds working neatly, because they've been constructed around easy-to-use quantities in that system. But metric recipes behave just as neatly, and are far more readily scalable, because the numbers are all just base 10, which everybody uses for everything all the time.

I know both. I can use both. I started out with imperial. But I choose to use metric, because metric is so very obviously superior. Yorkshire Pudding (talk) 15:17, 8 September 2025 (UTC)