I’m sure we’ve all seen memes where people complain their televisions are smaller than advertised, because they measure the width instead of the diagonal length. Big laughs at people who don’t know that TV screens are measured diagonally. But why are they measured diagonally?
I’m guessing that back in the olden days, cathode ray tubes used as television screens were round; thus the diameter was measured. When rectangular screens came out, the longest ‘diameter’ was measured. Am I right? Or is there another reason TV screens are measured diagonally?
That is the reason it started. In short time TVs standardized around 4:3 aspect ratio rectangle but they sounded bigger in the ads when measured on the diagonal so the practice remains to this day.
The diagonal is arguably a less ambiguous single measurement, when presented alone, than either the width or the height, without specifying which dimension is being stated.
Also, right up to the 1970s, the only practical way to mass-produce colour television tubes with three aligned electron guns was to make them round. For many years colour TVs looked like the picture below. A vague concept of rectangularity was produced by the frame cutting off the top and bottom of a perfectly round picture tube, but there was certainly no rectangular length and width that could be claimed.
It’s interesting that this not only has this convention persisted so as to be the metric for screens that are not TVs (smartphone screen sizes, for example), but also that inches seem to be the prevailing unit.
That might not be weird in the USA. It is a little bit weird in the UK (although survival of a few imperial measures is a thing here - beer and milk in pints, roads in miles), but for the rest of the world it must be weirder still.
-Unless in fully-metric parts of the world, screen sizes are not discussed in inches - I can’t easily tell from here, but packaging for consumer electronics tends to have the size emblazoned on the box, in inches and I am sure I’ve seen some European reviewers talk about smartphone screens in inches…
So… Non-USA/UK dopers… Are screen sizes in inches where you live? Is that weird?
German guy speaking. Here, the common practice is indeed to measure the size of screens (smartphones as well as computer monitors and TVs) in inches along the diagonal. We consider it weird in the sense that we don’t normally use inches (and don’t have an instinctive feeling for how much a given distance in inches is), but for this particular use case we’ve grown used to it.
Canada here. Supposed to be metric, but definitely not everywhere. Anyway TV screen sizes are in inches, and it’s not weird. Neither are golf courses or football fields in yards; or for that matter, horse racing in furlongs and miles. There are many other things we stick to in Imperial (pints of beer, for example), but those will do for now.
And we have low- and no-calorie soft drinks. I was surprised to find, on my first visit to Australia, that they have low-joule cola. I guess it’s metric, but I have no idea what a joule is. And like I said, we Canadians are supposed to be metric. If a joule is metric; well, we don’t use it.
Joule is the SI, i.e internationally standardised for scientific purposes, unit for energy. Since the chemical energy in food is a form of energy, it makes sense to use joules there too. The calorie is an old pre-SI unit for energy; its use in science is discouraged, but for nutritional purposes it’s still very common. FWIW, a calorie is defined as the amount of energy needed to heat up a gram of water by one Kelvin (or degree Celsius); but the “calories” you read on food labels are, in fact, kilocalories, i.e., a thousand calories.
If not inches, then cm. Milimeters are basically only used in construction/engineering, when the need for precision is high. For everyday measures, cm’s is used for objects up to a certain size. A washer will be 60 cm, a car vill be 4.55 m.
We still use inches in the metric world, e.g. tyres. Sound and studio equipment (19"). Analog audio tape is 1/8 (cassette) , 1/4, 1/2, 1 and 2. Even in construction, e.g. plumbing, some stuff exist as 1/4, 3/8, 1/2 and 1".
Amazingly, we people in the metric-land manage without freaking out, the way Americans do when confronted with metric.
Yes and yes. I know that one inch is equal to 2.53 cm, and I could do the calculation in my head. But then I’d be stuck with the diagonal in cm, and not knowing the ratio of the sides that seems pretty useless to me, so I go by the rule of thumb: more sounds better.
We also use inches for wheels, both for cars, motorcycles, and bicycles. What is the difference between 26" and 28" (I think those are normal bicycle sizes). Well, I guess 28" is bigger, so… er… it goes further? Or rather farther?
Measurements given in inches end up being abstract numbers in my mind, like the bit rate of the modems of yore. I never stopped to count the bits per second, I just knew the more, the better, assuming that the seller generously rounded up the numbers anyway.
And does the bezel count as part of the screen?
This is a great chance for me to be a smartass: Actually, it’s 2.54 centimetres (exactly; the precise length of the inch varies in the past but has now been set to exactly that value, to improve compatibility with metric/SI).
Oh, and since I’m an amateur astronomer, I’d like to add that the inch is also widely used for the focal length and mirror size of telescopes. For instances, the primary mirror of my Newton telescope has a diameter of 150 millimetres according to its label, but it’s not uncommon to hear such a device being referred to as a six-incher.
And that’s the point. Inches or cubits - it doesn’t matter. It’s not the actual size that’s important, it’s the comparative size. A 26-wheel is obviously smaller than a 28. A 46-TV is smaller than a 50.
1 Calorie = 4 kilojoules. Note that, for some idiotic reason, 1 Calorie = 1000 calories. There are two different units, of vastly different size, that are distinguished only by capitalization, and the capitalized one is the one that folk use for food.
Also note that food labels (in the US, at least, and probably most places) are allowed to round to the nearest integer Calorie. So something labeled “0 Calories” might actually have any amount up to 0.5 Calories. But that means that that same product, in Australia, might have up to 2 kilojoules. So it’s not true that 0 Calories = 0 joules.
The tires I’m most familiar with are bicycle tires, and for those, it is in fact millimeters (for instance, one common size for road bikes is 700 mm diameter). They’re also listed in inches, but the inch values are converted from the round-number metric values (that “27 inch” tire is actually 27.56 inches).
