Comment by hrbrtglm | Hacker News Reader

Comment by hrbrtglm | Hacker News Reader

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I love the metric system for no better reasons that it's the one I always used as a french, it just seems as natural for me as my ten fingers, I never really thought about it. Yet, I can understand why some would not change their “English customary measures”, they must feel it the same way, thinking it's as natural as their feet. For instance, our screens size (TV, computer, phones) are expressed in inches for whatever good reasons ... I don't have a clue at all about the size it represents, I just know 13 is smaller than 15, 11 is too small for me for a computer screen, and that 42 is a pretty good decent size for a TV. My surfboard is a 6.2, and for all I know, it's taller than me ...

If I were told, we were going to change our measure system, I would be kind of scared, could it be better or worse ! After all, the hardest part is not the real use but the idea of the switch.

Now, if you could just use the international ISO 216 paper size, I wouldn't have to mess with my PDF export settings and just push some A4.

I completely agree with you (even though you're French and I'm Italian ;)). I am used to metric system, but for some thing it's normal to use other measure we are used to. The example is exactly the one you're making, screen size for me it's normal to think about it in inches because it was always like this, and when sometimes I see TV screen sizes expressed in centimeters here in Luxembourg/Germany, I have to look for the conversion (or guess it sometimes from the model name) because I was thinking "42 is not enough, 50 is ok, 55 could be the right size for me, 60 is probably too much).

At the end it's mainly a matter of being used to, and being afraid of changing too

Screen size is measured as screen's diagonal.

It comes from the times when the screen were cathode-ray tubes. Late CRTs, as in old TV screens, were rectangular. But early CRTs were made circular for technological reasons, even if the device used a CRT as a rectangular screen. For a circular CRT, the diagonal of the rectangular "screen" part was just the diameter.

Since CRTs were invented long ago, and the first scanned video signal image was transmitted in 1907, the industry had time to develop a tradition which is not going to go now.

Inches to cm and back are actually an easy conversion so thinking in both isn't hard - 2.5cm/in, 30cm/ft. 1.6km/mi and 2.2 lbs/kg are a bit more annoying, and Fahrenheit are a freaking abomination.

C is roughly (F - 30)/2, not too bad. To make my life easier I also measure lb as 1/2 kg and driving distances as time.

> C is roughly (F - 30)/2, not too bad.

A few months ago, I was concerned about the inaccuracy of this rough conversion. It's actually accurate to within ±3°F for all temperatures -5°C to 25°C (23°F to 77°F). If you're OK with ±5°F, it works for -15°C to 35°C (5°F to 95°F).

So the conversion works pretty well for the vast majority of environmental conditions. C = (F - 30) / 2 and F = C * 2 + 30 are great approximations.

I still remember the formula by heart C=5/9*(F-32), learned it a kid while reading books on electronics. Mentally I still use it to convert while watching a movie for example. However I still don't know how people prefer it over Celsius, the latter feels a lot more natural.

Pound to Kg is rather easy as it has to be multiplies by 2.2, adding 1/10 after multiplying by 2.

My screen to paper size conversion:

15 inches is almost exactly A4 landscape 17 inches has a 2cm gap around the edges 19 inches has a 5cm gap around the edge 24 inches is A3 landscape or 2.5xA4 in portrait mode.

For such a conversion, you may need however to specify a screen aspect ratio, because even if the diagonal remain the same size, the height or with will vary regarding a 4:3, 16:9 or 16:10 screen.

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