Please explain aspect ratio?

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I’m just not getting how it works. Can someone explain aspect ratio to me like I’m literally five lol?

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It’s just a measure of how wide a picture is compared to how tall it is. Old TVs were usually 4:3, so 4 parts wide to 3 parts tall. Newer stuff is usually wider.

Let’s draw a picture. If it’s a rectangle, it has a length and width. Let’s say it’s a small picture, 2 inch x 1 inch. It’s ratio is 2:1. Now let’s make a bigger one. Maybe 6 inch x 3 inch. So 6:3. But 6 is twice as big as 3, so the ratio is still 2:1.

Computers and other displays use much bigger numbers of pixels, but still have a ratio. 4000 x 3000 would be 4:3, but so would 8000 x 6000.

Hope that helps.

It’s the ratio of how wide an image is compared to it’s height. It’s expressed as a value x:y, x being horizontal, y being vertical, and it’s the lowest numbers you can use to express the differences, for example you would never see 32:18 aspect ratio monitors because they’re the same as 16:9. It’s easiest for me to think of it as actual pixels. For example 1920×1080 is 16:9, which means that for every 9 pixels there are vertically, there are 16 horizontally.

Or another example, some ultrawide monitors are 21:9, which means for every 9 pixels up there are 21 across.

Do you know ratio’s in general? If yes than it’s just ratio’s but for images. The first number shows the amount of x pixels, x meaning the pixels that go horizontally and the second number shows the amount of y pixels, y meaning the pixels that go vertically. So a aspect ratio shows just like other ratios how much there is of one unit, in this case x pixels, and another unit. In this case the y-pixels. So an aspect ratio just shows for example with 4:3. That for every 4 x-pixel so every 4 pixels in width, theres 3 pixels in height.

Edit: It doesn’t have to be pixels if its not an digital image, it can also be centimetre, metre etc. Just like any other ratio.

Looking at your tv, is it a rectangle? One side is longer than the other….it’s wider than it is tall. It’s 16 units wide, and 9 units tall. So, the aspect ratio is 16 by 9. It’s a measurement of height and width, relative to each other.

As others have explained, it’s the ratio of an image’s width to height.

It matters because you might want to display an image which was made with one ratio on a screen with a different ratio. So then you’ve got to stretch it in one dimension or scrunch it in the other, distorting the image.
Or crop it on one or two sides, losing part of the image.

So I measured a business card. If it’s 3.5 wide x 2 tall, is going to be 3.5:2?

Old TV’s used to be rather square. Cinema screens used to be wide rectangles, and newer TV’s and computer screens started adopting that wider shape. Phones are now even wider than computer screens.

So in order for people to talk about all these different screen shapes, they came up with just saying how wide a screen may be vs. how tall it is. 4:3, 16:10, etc., these are ratios of wide:tall.

While everyone has covered electronics, I’ll cover Aspect Ratio from the automotive side. In cars Aspect Ratio refer’s to a tire’s sidewall height in relation to its tread width.

If you look on the side of your tires you will see a number like: 225/45 R17. The first number “225” is the tire’s tread width in mm. The number after the slash is the Aspect Ratio: “45.” This means the tire’s sidewall height is 45% of the tread’s width. So in this example the tire’s sidewall is 101.25 mm high (225*0.45=101.25).

So if I’m upscaling or downscaling an image to a custom aspect ratio, what’s the new unit of measurement I need to use? This is where I’m falling short.

Thanks everyone. I’m beginning to grasp the concept. I’ve never had to use aspect ratio. Well I decided that I’d start sharing some of my sketches on Pinterest. But I tried several times to get my pin to show up in Portrait format, but it always came out sideways. My image was already portrait format on a site that only uses portrait format. And Pinterest says there pin system is intuitive? Yeah right lol. Then I learn I’ve got to format the image to 2:3 aspect ratio. So that’s how this all came up.

I digress though. Thanks for trying to help me understand aspect ratio everyone. I greatly appreciate it. 😀

The aspect ratio is a number that tells you how tall or wide a rectangle is.

For the ELI5 metaphor, let’s look at some flat Lego bricks…

These come in a wide variety of shapes, square, wide, long, etc… And the aspect ratio is used to describe this.

If you were to take a plate that is two studs tall by four studs wide, we can work out the aspect ratio by counting those studs – it has an aspect ratio of 4:2 (which we can simplify slightly by dividing each number by the same amount – in this case by two to get an aspect ratio of 2:1).
If you have a longer plate that is two studs tall and eight long, the aspect ratio would be 8:2 (or 4:1).
Look at a square plate of two studs by two studs and that is an aspect ratio of 2:2 (or 1:1).

The aspect ratio tells you how long one side is compared to the other, so we can scale this up or down to get plates that are the same shape, but different sizes – our 2:1 ratio plate could be the four by two plate mentioned above, it could also be a two by one, or an eight by four – these are all the same shape and correspond to a ratio of 2:1.