My erect wiener is 12 inches long. While this is not always a convenient metric, it works for distances less than a mile.
I am a cashier in a hardware store. Most of the boards are unmarked, so I have to be able to figure out the sizes. A six-foot board is about as tall as your average contractor when he holds it up next to him. A twelve-foot board will hit the ductwork above the registers. Twenty-foot boards are kept outside, so I don’t have to see them at all. The only thicknesses are one and two inch, and they are easy to tell apart.
I can also recognize white pine, treated pine, cedar, poplar, and red oak by color/texture.
I am pretty good with all measurements, and eyeballing stuff weather it is a cup, a foot, or a mile.
I also was a cashier for a few years at a store that sells everything, including a lot of lumber, nails etc. I could almost always guess the right board length, before I had to look it up in a book to find the code. This was before UPC’ codes and scanners, so we had to look stuff up and enter it all by hand.
I cannot tell you the amount of times some contractor guy would be like, “Oh honey, let me help you”, and I would shock them by getting all of their order right.
It just seems easy to me.
I’m excellent at estimating almost any everyday ‘measurables’, including outdoor temperature and time. One of the hardest things is, perhaps suprisingly, estimating the weight (mass) of something in the <1 kg category by hand. I’m not alone in this regard.
The same has been true for me. The innate knowledge of the centimeter has always given me the upper hand in understanding the metric system.
I am especially crappy at estimating people in a crowd. If I go to a party or concert, and you ask me how many people are there, I am really incapable of telling you if there are 200 or 800 people there. I can count to 20 and then try to figure how many groups of 20 are there, but it just doesn’t work for me.
I’ve never understood how when there’s a police report, they always list the height and weight of the suspect. How do people learn to estimate these things? I see lots of people, but I don’t know how much most of the people I know weigh, so I don’t know what a 250-pound person looks like vs a 215 pound one, especially of different builds and heights. Now, regarding height, I imagine you could get a rough idea just by seeing if the person is shorter or taller than yourself, but I don’t know how it is that people are able to judge people’s weights unless maybe they have a a background in athletics where people are weighing in all the time.
I think it’s just experience. I used to work in a cabinet shop with an old guy named Russ. He’d be standing at the chop saw, and I would come over to cut a single piece of wood:
“How long do you want it?”
“17 and 5/16ths.”
He grabbed my board, and cut away. The board was 17 and 1/4". He did not use a tape measure, and there was no tape on the rail either. I saw him do this on many occaisions, and never more than 1/8th of an inch off; it always seemed weird to me.
I used to be able to glance at a bolt head and pick up the right wrench without thinking about it. I could do that with both Metric and American sizes. But I cannot estimate distance in either measuring system nor can I convert one to another. I’m fair at guessing the weight of people but I cannot begin to estimate the weight of a block of stone. As a kid, though, I was pretty good at estimating the weight of a bale of cotton as soon as it came out of the baling machine.
I once worked with a mechanic who had the ability to estimate the thickness of a shim by rubbing it between his forefinger and thumb; he could also move his hand down a cylinder of an engine while using his thumb and little finger as guides and then very accurately tell the amount of taper in that cylinder. In the same way, he could estimate the size of crank and cam shaft journals. And he could make those estimates in both American and Metric sizes. Uncanny.