Aspect Ratio Finder

Figure out the exact ratio of any image, or calculate the dimensions you need for a target ratio. Everything runs right here in your browser.

Find Your Image’s Aspect Ratio

Upload an image to auto-fill its size, or type the dimensions in yourself.

Click to upload an image (optional) – used only to read its width and height

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Calculate Dimensions From a Ratio

Know the ratio you need? Enter it plus one dimension to get the other.

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Fill in only one of Known Width or Known Height – the other is calculated for you.

How to Find an Aspect Ratio

Upload or type dimensions

Drop in an image to auto-read its size, or just type the width and height yourself.

See the simplified ratio

The tool reduces your dimensions down to the simplest whole-number ratio automatically.

Calculate new dimensions

Need a specific ratio at a different size? Use the second calculator to solve for the missing side.

Common aspect ratios and where they are used

An aspect ratio is the shape of an image, written as width : height. These are the ones you will run into most often, with a typical size for each.

Ratio	Typical sizes (px)	Where you see it
1:1	1080 x 1080	Square social posts, profile pictures
4:5	1080 x 1350	Instagram portrait posts
3:2	3000 x 2000	Photos from most DSLR and mirrorless cameras
4:3	1600 x 1200	Older monitors, many tablets, compact cameras
16:9	1920 x 1080, 1280 x 720	HD video, YouTube, most monitors and TVs
9:16	1080 x 1920	Stories, Reels, TikTok
21:9	2560 x 1080	Ultrawide monitors, cinematic video

To work one out by hand, divide the width and the height by the biggest number that goes into both. For 1920 x 1080 that number is 120, which leaves 16 and 9. To find a missing side, use the ratio the other way round. For a 16:9 image that is 1280 pixels wide, the height is 1280 divided by 16, times 9, which gives 720.

Once you know the shape you need, the crop tool gets your image to that shape and the resize tool sets the exact size.

Frequently Asked Questions

What is an aspect ratio?

It is the relationship between an image’s width and height, written as two numbers like 16:9 or 4:3. It describes the shape of the image regardless of its actual pixel size – a 1920×1080 image and a 1280×720 image both share the same 16:9 ratio.

Why do platforms like Instagram or YouTube care about ratio?

Each platform displays images and video in specific shapes. Uploading the wrong ratio often means your content gets cropped or padded with bars. Common targets are 1:1 for square posts, 4:5 for portrait feed posts, 9:16 for stories and reels, and 16:9 for standard video.

Does changing the ratio crop or stretch my image?

This tool only calculates numbers – it does not modify your actual image file. If you need to physically change an image to match a ratio, use the Crop Image or Resize Image tools instead.

Is my image uploaded to a server?

No. If you upload an image here, it is only read locally in your browser to measure its width and height. The file itself never leaves your device.

Can I use decimal dimensions?

The calculators are built around whole-number pixel dimensions, since that is how images are actually measured. Rounding may occur when a calculated dimension is not a whole number.

Is this tool free to use?

Yes, completely free with no account required and no limit on how many times you use it.

What is the aspect ratio of 1920 x 1080?

16:9. Both numbers divide by 120, which leaves 16 and 9. The sizes 1280 x 720 and 3840 x 2160 are also 16:9.

How do I calculate the height for a given width?

Use the second calculator. Enter the ratio, such as 16 and 9, then type the width you want in the Known Width box and the height appears. For example, a width of 1280 at 16:9 gives a height of 720.

What aspect ratio should I use for Instagram?

Square posts are 1:1, portrait posts are 4:5, and Stories and Reels are 9:16. Instagram changes its layout from time to time, so check its current guidance if you need exact numbers.

What aspect ratio is my phone photo?

Most phones shoot 4:3 by default, and many also offer 16:9 or 1:1. Upload your photo here and the tool will show you the exact ratio.