How do I say "An aspect ratio of 4:3" and proportions?

Question

When you deal with images you have to mention aspect ratios, that are written as "16:9", "4:3" etc. and image dimensions that are written as "480x320", "3840x2160", etc.

How do I say these?

1. I suppose aspects ratios would be pronounced as 4 by 3, or 16 by 9, right?
2. I suppose "by" will be used on image dimensions too, right?
3. Another doubt of mine: how do I say, in these cases, the numbers? For example, "four eight zero by three two zero" or "four hundred and eighty by three hundred and twenty? "three eight four zero by two one six zero" or "three thousand eight hundred and forty by two thousand one hundred and sixty"?

thanks

Answer 1

An image size 480x320 is usually said to be

480 by 320

An aspect ratio of 16:9 is usually said to be

16 to 9

Whether you say each digit individually or narrate the number is a matter of context and choice. For example "16 to 9" would never be said as "one six to nine" (except possibly in a strict environment), likewise it is more usual to say "four-eighty" than "four eight zero".

Larger numbers might be clearer if spoken digit by digit, for example it would probably be clearer to say 1048576 (2²⁰) in its digits, rather than

One million, forty-eight thousand, five hundred and seventy-six.

Answer 2

Aspect ratios are usually pronounce 4 to 3, 16 to 9, for examples, just like other ratios.
The preposition by is normal for absolute resolution values, like 480x320, as opposed to relative sizes, like 16:9.

Answer 3

I'll mention that in addition to using "by" or "to" between aspect ratio numbers, it's also reasonably common to drop the preposition entirely - you may hear some call it a "four three" or "sixteen nine" aspect ratio. For the resolution numbers themselves, you wouldn't usually drop the preposition, so you'd only rarely if ever hear "nineteen twenty ten eighty" rather than "nineteen twenty by ten eighty". "By" would also usually be the preferred preposition here for resolution numbers.

For pronouncing the actual resolution numbers, I'd say there are only a few common ones that are "standardized" like 1080 being pronounced "ten eighty" or 1920 being pronounced "nineteen twenty". I'd probably keep the same convention of pronouncing it as two double-digit numbers for less common resolutions, like "thirty-eight forty by twenty-one sixty". For three-digit numbers, it's common to say it as a single digit number followed by a double digit number, like "four eighty" or "seven twenty".