5 ms·

The strange thing about articles like this is that they seem to assume that converting between units is something that happens all the time, such that doing so

The strange thing about articles like this is that they seem to assume that converting between units is something that happens all the time, such that doing so is a huge drain on the economy and engineering time. I don't know if my experience is the common one - but with a few exceptions (inches/feet, oz/pounds) such conversions seem kind of rare. Instead, you pick an appropriately sized unit to begin with, and stick with it. It's interesting to note that all of the examples the article gives are caused by metrication - which forces conversions - rather than by problems using the customary units. I don't see the point of a half-assed metrication, where everything remains the same size but is measured in centimeters. (Such that lumber is sold in lengths of 243.82 cm rather than 8 feet.) The US is already half-assed metric in a lot of places, with both customary and metric units printed on packaging when appropriate. I guess the question is - what are the benefits of metrication that justify the massive expense required to convert?

privong 12y ago
> (Such that lumber is sold in lengths of 243.82 cm rather than 8 feet.) It's interesting that you pick that example. In many cases, the "measurements" for lumber don't actually correspond to the true dimensions of the product purchased. For example, a "2x4" has dimensions of 1 1⁄2 inches x 3 1⁄2 inches[0], rather than 2 inches by 4 inches. So, at least for the example you give, it's not clear to me that converting to metric is a bad idea, since the specifications are already somewhat nonsensical. Granted, a "2x4" does have a standard size. [0] https://en.wikipedia.org/wiki/Lumber#North_American_softwoods https://en.wikipedia.org/wiki/Lumber#North_American_softwood...
- happyscrappy 12y ago
  It is not nonsensical, 2x4 is the rough sawn size. Edit: Since I can't reply because of HN's helpful 'You're submitting too fast' notice, I will reply here. You can still buy rough sawn for working on existing structures and for aesthetics when exposed.
  - privong 12y ago
    I don't have primary source info, but from the wiki article I linked, that used to be the case, but is no longer the case. All that matters now is the final cut dimensions.
- pge 12y ago
  Having worked in construction, I think it is the last point you make that is most important. Though a 2x4 is 1.5x3.5, it is a standard dimension. In the US, construction standards (lumber sizes, door frame sizes, ceiling heights, etc) are all in feet and inches. Changing them creates a compatibility nightmare. That said, I don't know of other industries that suffer the same challenge (perhaps others can think of them). Bicycles for examples transitioned reasonably quickly from English standards (e.g. 1 in. stems and 27 in. wheels) to fully metric for road bikes at least.
- benjohnson 12y ago
  Oddly enough - Depending on the market, European plywood is sold as 125x250 cm sheets, but when you measure them they can be a bit larger. When you measure them - they're exactly 4 x 8 feet as if they were for Americans. It's also why you find a lot of 10mm 13mm and 19mm bolts that suspiciously also fit 7/16 1/2 3/4 inch sockets.
bryanlarsen 12y ago
The point is that the US would be half-assed metric whether it wanted it or not because it's part of the global economy. So your choices are half-assed metric or full on metric. There are no other choices.
icegreentea 12y ago
I am not sure if this fully answers your questions, but one of the places where unit conversions happens a lot when doing customary unit engineering calculations is dealing with various constants/properties. For example, you might get the specific heat capacity of some material in terms of gallons, but you're dealing with ounces of fluid, and so you stick a conversion in there. It's certainly kind of niche, but it's really annoying to deal with. But agreed on the half-assed metrification. I'm from Canada. I still buy pop and beer in 355ml cans, 591ml coke bottles, 600ml pepsi bottles, and 2L big bottles. My wood is still sized in inches (or nominal inches). (I fully support SI though. In theory, I no longer need to memorize a whole set of conversion constants. In practice, I live in Canada, so I still need them).
- maxerickson 12y ago
  Shouldn't a bottle of pop or beer prioritize a sensible number of servings (1,2,etc.) over a round number of units? It's not like "I need 42 liters of beer for my guests, how many cans is that" is going to be a common thought process.
cs02rm0 12y ago
Probably a host of stuff from one less NASA orbiter crashing, down to not having the sticker on millions of car B pillars printed with imperial and metric tyre pressures. There are lots of downsides, it's interesting you give a construction example; in the UK we have houses built from imperial bricks. Metric bricks aren't the same size, but a conveniently round number in millimetres. A house I'm buying was built in imperial bricks and someone with not quite enough sense has filled in some old doorways with metric bricks. The costs of maintaining different systems aren't large but accumulate indefinitely, the cost to switch is finite.
- trothamel 12y ago
  Again, it's interesting that all of those are issues caused by metrication, the switch to metric units, rather than issue caused by customary or imperial units themselves. > The costs of maintaining different systems aren't large but accumulate indefinitely, the cost to switch is finite. That only makes sense if there's no discount rate, nothing else that could be done with the money we'd spend to switch. I suspect there are a lot of things that could be done that would yield higher rewards.
cpwright 12y ago
Because I don't want to look at 243.82cm on my tape measure, or if I am trying to lay something out to match the 16 in on center studs 40.64 cm, 81.82, 121.92, 162.56, 203.2, and then 243.82 cm. For new stuff you could probably cheat and just base it on 40cm, which would be fine and perfectly acceptable, but for the old stuff which is still out there over the 8 feet, I'm already off by more than an inch which is enough to not hit the stud. Most framing isn't great, but still the error is additive and fractions are hard enough to work with that I'd want to avoid it. I think the transition for lots of things really has an additional cost. Is that speed limit sign metric or imperial? Sometimes its obvious, other times not, and there are thousands and thousands of different governments responsible for them.

privong 12y ago

> (Such that lumber is sold in lengths of 243.82 cm rather than 8 feet.) It's interesting that you pick that example. In many cases, the "measurements" for lumber don't actually correspond to the true dimensions of the product purchased. For example, a "2x4" has dimensions of 1 1⁄2 inches x 3 1⁄2 inches[0], rather than 2 inches by 4 inches. So, at least for the example you give, it's not clear to me that converting to metric is a bad idea, since the specifications are already somewhat nonsensical. Granted, a "2x4" does have a standard size. [0] https://en.wikipedia.org/wiki/Lumber#North_American_softwoods https://en.wikipedia.org/wiki/Lumber#North_American_softwood...

happyscrappy 12y ago
It is not nonsensical, 2x4 is the rough sawn size. Edit: Since I can't reply because of HN's helpful 'You're submitting too fast' notice, I will reply here. You can still buy rough sawn for working on existing structures and for aesthetics when exposed.
- privong 12y ago
  I don't have primary source info, but from the wiki article I linked, that used to be the case, but is no longer the case. All that matters now is the final cut dimensions.
pge 12y ago
Having worked in construction, I think it is the last point you make that is most important. Though a 2x4 is 1.5x3.5, it is a standard dimension. In the US, construction standards (lumber sizes, door frame sizes, ceiling heights, etc) are all in feet and inches. Changing them creates a compatibility nightmare. That said, I don't know of other industries that suffer the same challenge (perhaps others can think of them). Bicycles for examples transitioned reasonably quickly from English standards (e.g. 1 in. stems and 27 in. wheels) to fully metric for road bikes at least.
benjohnson 12y ago
Oddly enough - Depending on the market, European plywood is sold as 125x250 cm sheets, but when you measure them they can be a bit larger. When you measure them - they're exactly 4 x 8 feet as if they were for Americans. It's also why you find a lot of 10mm 13mm and 19mm bolts that suspiciously also fit 7/16 1/2 3/4 inch sockets.

bryanlarsen 12y ago

The point is that the US would be half-assed metric whether it wanted it or not because it's part of the global economy. So your choices are half-assed metric or full on metric. There are no other choices.

icegreentea 12y ago

I am not sure if this fully answers your questions, but one of the places where unit conversions happens a lot when doing customary unit engineering calculations is dealing with various constants/properties. For example, you might get the specific heat capacity of some material in terms of gallons, but you're dealing with ounces of fluid, and so you stick a conversion in there. It's certainly kind of niche, but it's really annoying to deal with. But agreed on the half-assed metrification. I'm from Canada. I still buy pop and beer in 355ml cans, 591ml coke bottles, 600ml pepsi bottles, and 2L big bottles. My wood is still sized in inches (or nominal inches). (I fully support SI though. In theory, I no longer need to memorize a whole set of conversion constants. In practice, I live in Canada, so I still need them).

maxerickson 12y ago
Shouldn't a bottle of pop or beer prioritize a sensible number of servings (1,2,etc.) over a round number of units? It's not like "I need 42 liters of beer for my guests, how many cans is that" is going to be a common thought process.

cs02rm0 12y ago

Probably a host of stuff from one less NASA orbiter crashing, down to not having the sticker on millions of car B pillars printed with imperial and metric tyre pressures. There are lots of downsides, it's interesting you give a construction example; in the UK we have houses built from imperial bricks. Metric bricks aren't the same size, but a conveniently round number in millimetres. A house I'm buying was built in imperial bricks and someone with not quite enough sense has filled in some old doorways with metric bricks. The costs of maintaining different systems aren't large but accumulate indefinitely, the cost to switch is finite.

trothamel 12y ago
Again, it's interesting that all of those are issues caused by metrication, the switch to metric units, rather than issue caused by customary or imperial units themselves. > The costs of maintaining different systems aren't large but accumulate indefinitely, the cost to switch is finite. That only makes sense if there's no discount rate, nothing else that could be done with the money we'd spend to switch. I suspect there are a lot of things that could be done that would yield higher rewards.

cpwright 12y ago

Because I don't want to look at 243.82cm on my tape measure, or if I am trying to lay something out to match the 16 in on center studs 40.64 cm, 81.82, 121.92, 162.56, 203.2, and then 243.82 cm. For new stuff you could probably cheat and just base it on 40cm, which would be fine and perfectly acceptable, but for the old stuff which is still out there over the 8 feet, I'm already off by more than an inch which is enough to not hit the stud. Most framing isn't great, but still the error is additive and fractions are hard enough to work with that I'd want to avoid it. I think the transition for lots of things really has an additional cost. Is that speed limit sign metric or imperial? Sometimes its obvious, other times not, and there are thousands and thousands of different governments responsible for them.