Poor old imperial system doesn't deserve the trash talk it gets. In general, each of the units occupy their own domain with little cross between. For example:

Distant location: **Use miles**

Visible/walking distance: **Use feet/yards**

Dimensions of small object: **Use inches**

Difficult to see: **Use mils**

It is of course immaterial what the exact size of a unit is. An inch is an inch and a cm is a cm. One is not "better" than the other and each is equally ugly when expressed as a multiple of the other. Where the SI system has got it right however is the consistency of defining quantities within the system using powers of ten, and defining units using other units so you end up with multipliers of 1 nearly always. It is a true

*system* in other words.

What i see as the curse of the imperial system is precisely this lack of systemic approach. Imperial dimensions are domain specific and while they work inside a problem domain, they do not do so well universally. Add to that historical and regional variations in identically named units and the brothel is ready go into business...

For cases that fall between these domains, I never see decimal values so conversion factor doesn't often come into play. For example, if someone is 5ft 9in tall, I can imagine a length of 5 feet and I could imagine 9 inches above that. I don't try to imagine 5.75 feet.

Sorry but that is just BS. Maybe it works for you in this particular case but generally we who are accustomed to calculating in SI units look round eyed at the swamps of conversion factors and magic multipliers that the imperial formulas are full of. Yes you can do it but to me it looks like pulling wisdom teeth via your asshole. The only semi good argument i have heard for imperial measurements is that a wee dram tastes better than a wee 3 or 4 cl (whatever dram was, i forget).

I would imagine this is the same for all of you used to the metric system. Why would anyone need to factor in the fact that there are 1000 meters in a kilometer if just measuring height or some furniture? Why should I care that there are 1000 mm in a meter when fitting parts for a pcb?

No, actually it is not the same at all, and this is the point i have been trying to make. It is a completely different mindset where you live in a world where there is one unit of measurement per one physical quantity. You then just apply the prefix that scales the unit reasonably. Dimensions for more complex quantities are (almost) logically derived from simple ones using the units of those simpler dimensions. It is a system you can and learn to trust so much that it effectively becomes invisible; if someone needs a 3 mm thick piece of aluminium sheet there is no ambiguity and no need to memorize gauges of this and gauges of that; diameters or radii of drill holes are not suddenly given in fractional presentation and wire sizes in yet another gauge making no sense to those who only know linear dimension units. If i need to find out whether a 1.5 mm^2 wire will carry a given current without overheating, i plug that cross section (or any other cross section) into the formula without first converting it from a presentation unusable, or usable only with extra unhelpful and unneeded conversions. If i need a liter of oil for my car or lawnmower, i don't need to worry whether it is a EU liter or someone else's liter, even when traveling.

The ultimate point perhaps is that you _never_ need to worry/wonder whether you are using the "best" or "correct" dimensions in a calculation. Say you start figuring the distance from earth to the sun in millimeters and later realize that this was perhaps not the optimal choice after all, no problemo. Just divide by 10^6 i.e. shift the decimal point 6 digits and you are in kilometers.

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Sorry, didn't mean to rant.