Common Aspect Ratios: The Complete List With Examples

What are the most common aspect ratios?

The most common aspect ratios are a short list of shapes that screens, cameras, and apps have standardized over the years. You’ll meet maybe eight of them in daily work, and 16:9 alone covers about 90% of the video you watch online.

Here’s the full chart. Each row shows the ratio, its decimal value, where you’ll find it, and a sample resolution that fits the shape exactly.

Ratio	Decimal	Where it’s used	Example resolution
16:9	1.78	HDTV, YouTube	1920x1080
4:3	1.33	Old TV, iPad	1024x768
3:2	1.5	DSLR, 35mm film	3000x2000
21:9	2.33	Ultrawide, cinema	2560x1080
1:1	1.0	Instagram	1080x1080
9:16	0.56	Reels, Stories, TikTok	1080x1920
2.39:1	2.39	Cinemascope	1920x803
5:4	1.25	Large-format photo	1280x1024

A couple of patterns jump out of that list. Anything wider than 1.0 is landscape, and the higher the decimal climbs, the wider and shorter the frame gets. The 9:16 ratio is the only one under 1.0 here, which is why it’s so tall. If you want the full background on what these numbers mean, our guide on what is aspect ratio breaks down the formula from scratch.

What is the 16:9 aspect ratio?

The 16:9 aspect ratio is today’s default widescreen shape, sitting at a decimal of 1.78. It’s 16 units wide for every 9 units tall, and it’s what your TV, your laptop, and nearly every YouTube video use. You’re looking at it right now, probably.

This ratio won because it’s a sensible middle ground between the old boxy 4:3 and the very wide cinema formats. A 1920x1080 frame (Full HD) is the most quoted 16:9 size, but it isn’t the only one. Both 1280x720 and 3840x2160 (that’s 4K) share the exact same shape, so they all fill a 16:9 screen with no black bars.

Because it’s everywhere, 16:9 is the safe export when you’re not sure. YouTube wants it, HDTV broadcasts it, and most monitors display it natively. If you’re building a thumbnail to sit on top of one of these videos, the YouTube thumbnail size is 1280x720, which is 16:9 too. When you need to lock exact pixel pairs, the 16:9 calculator does the arithmetic in a second.

What are 4:3 and 5:4 used for?

The 4:3 and 5:4 ratios are the squarer, older shapes that ruled screens before widescreen took over. The 4:3 ratio (decimal 1.33) was the standard for tube TVs and early computer monitors, and it’s still the native shape of the iPad.

You’ll bump into 4:3 more than you’d expect. Projectors and slide decks often default to it, vintage photos use it, and a sample resolution is 1024x768. It’s a comfortable shape for documents and presentations because it doesn’t waste vertical room the way ultrawide formats do. When you scan an old family print, there’s a good chance it’s 4:3.

The 5:4 ratio (decimal 1.25) is even squarer and shows up in large-format photography and a handful of older monitors at 1280x1024. It’s rare now, but it hasn’t vanished. If you’re prepping print work where physical inches matter more than pixels, our inches to pixels tool converts the measurements so you don’t have to guess.

What are the vertical and square ratios?

The vertical and square ratios are built for phones and feeds, and they’ve exploded since mobile took over. About 75% of web traffic now happens on phones, so a tall frame fits the device far better than a wide one does.

The 9:16 ratio is the big one. It’s just 16:9 flipped on its side, with a decimal of 0.56, and it powers Reels, Stories, and TikTok at 1080x1920. This shape fills a phone screen top to bottom with no wasted space, which is exactly why short-form video looks so immersive. If you shoot a clip the wrong way around, you’ll get ugly black bars on the sides, so it pays to rotate before you record.

The 1:1 square ratio (decimal 1.0) is the other mobile staple, sized at 1080x1080 for Instagram feed posts. It’s the only shape that never favors width or height, so it crops cleanly either way. Instagram also loves 4:5 portrait posts because they’re taller and grab more screen, but 1:1 stays the classic feed shape.

What are the cinema ratios (21:9 and 2.39:1)?

The cinema ratios are the widest shapes you’ll meet, designed to wrap the viewer in the picture. The 21:9 ratio (decimal 2.33) drives ultrawide monitors at 2560x1080, and it’s a favorite for editing timelines, spreadsheets, and gaming where extra horizontal space helps.

It isn’t truly 21:9 in the math, since 2560 divided by 1080 lands at 2.37, but the industry rounds it to 21:9 as a label. Either way, it’s noticeably wider than 16:9, so a single ultrawide screen can replace a dual-monitor setup for a lot of people. Film editors like it because a 2.39:1 movie almost fits inside it.

That brings us to 2.39:1, the modern cinemascope or anamorphic widescreen standard for feature films. A frame like 1920x803 gives you that letterboxed, theatrical look, and it’s why movies show black bars when you watch them on a 16:9 TV. The film is simply wider than the screen, so the bars fill the gap. It’s the widest standard on this list by a clear margin.

How do you choose the right aspect ratio?

You choose the right aspect ratio by matching it to where the image will live, not by personal taste. Each platform expects a specific shape, and uploading the wrong one means cropping, black bars, or a rejected file. Decide the destination first, then pick the ratio.

Here’s a quick map you can lean on:

• YouTube and TV: 16:9 at 1920x1080
• DSLR and 35mm photography: 3:2 at 3000x2000
• Instagram feed: 1:1 at 1080x1080, or 4:5 for portrait
• Reels, Stories, TikTok: 9:16 at 1080x1920
• Ultrawide monitor or gaming: 21:9 at 2560x1080
• Feature film look: 2.39:1 at 1920x803

The rule that saves the most headaches is simple. Don’t shoot or design first and force the shape later, because you’ll lose pixels in the crop every time. Pick the home, match its ratio, then push resolution as high as your file budget allows. That order keeps faces from stretching and headlines from getting chopped.

How do you calculate or convert a ratio?

You calculate an aspect ratio by dividing the width by the height, then simplifying both numbers by their greatest common divisor. For 1920 by 1080, the GCD is 120, so each side divides down to 16:9. The decimal check is 1920 divided by 1080, which equals 1.78.

The same method works for any size you throw at it. A 3000x2000 photo shares a GCD of 1000, which reduces to 3:2. A 1280x1024 image divides by 256 to give 5:4. You’re just hunting for the smallest whole-number pair that holds the proportion, and if the numbers don’t reduce cleanly, the decimal still tells you the shape.

You don’t need to do any of this by hand, though. Drop your pixel dimensions into the aspect ratio calculator and it returns the simplified ratio plus the decimal instantly. Need to resize while keeping the shape? It’ll fill in the matching side for you, so you won’t accidentally stretch the frame. Once you’ve used it a few times, you’ll start recognizing 16:9, 4:3, and 9:16 on sight, and the math becomes a formality you rarely touch.