How to Use Our Aspect Ratio Calculator
To find your new dimensions, you just need to know the original size of your image or video and one of the new dimensions you want to achieve.
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Original Width: Enter the width of your original image or video in pixels (px).
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Original Height: Enter the height of your original image or video in pixels (px).
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New Width OR New Height: Enter one of the new dimensions you’re aiming for. For example, if you know your image needs to be 800px wide, enter “800” in the “New Width” field. The calculator will automatically solve for the corresponding height to maintain the aspect ratio.
Understanding Your Results
The calculator provides the missing dimension (either the new width or new height) required to maintain the original aspect ratio.
Aspect ratio is simply the proportional relationship between the width and height of a rectangle. It’s often written as two numbers separated by a colon, like 16:9 or 4:3. When you resize an image, you must scale both the width and height by the same factor to keep this ratio intact. If you don’t, the image will look stretched, distorted, or squashed.
The Math Behind the Proportions
Our calculator uses a simple cross-multiplication formula to ensure the proportions stay the same. The core principle is:
Original HeightOriginal Width=New HeightNew Width
So, if you provide a new width, the calculator solves for the new height with this formula:
New Height=Original WidthOriginal Height×New Width
This guarantees that your resized image or video is a perfectly scaled version of the original.
Common Aspect Ratios & Their Uses
Different mediums and platforms are optimized for specific aspect ratios. Understanding these can save you a lot of time. Here’s a quick guide:
Frequently Asked Questions About Aspect Ratio
What is the most common aspect ratio?
For video, the most common aspect ratio today is 16:9. It’s the standard for HDTVs, YouTube, Vimeo, and most modern computer monitors. For photography, 3:2 and 4:3 are very common, as they correspond to the sensor sizes of most DSLR and mirrorless cameras. For social media feeds, 1:1 (square) and 4:5 (vertical) are extremely popular.
How do I find the aspect ratio of an image?
You can find it by dividing the width by the height. For example, an image that is 1920 pixels wide and 1080 pixels high has a ratio of 1920 / 1080 = 1.777.... This corresponds to the 16:9 aspect ratio (16 / 9 = 1.777...). You can also use online calculators or check the file’s properties on your computer.
Why is my video showing black bars?
Black bars appear when the aspect ratio of your video does not match the aspect ratio of the screen you’re viewing it on. This is called letterboxing (bars on top and bottom) or pillarboxing (bars on the left and right). For example, watching a cinematic 21:9 movie on a standard 16:9 TV will result in letterboxing because the movie is wider than the screen. The player adds black bars to fill the empty space without distorting the image.
What is the best aspect ratio for Instagram?
It depends on where you’re posting:
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Instagram Feed Posts: You can use square (1:1), landscape (up to 1.91:1), or portrait (up to 4:5). For maximum screen real estate in the mobile feed, a 4:5 aspect ratio (e.g., 1080×1350 pixels) is best.
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Instagram Stories & Reels: Use a vertical 9:16 aspect ratio (1080×1920 pixels). This fills the entire mobile screen for an immersive experience.
What does it mean to “maintain aspect ratio”?
It means keeping the original proportions of an image or video when you resize it. Imagine a photograph of a person. If you resize it but don’t maintain the aspect ratio, the person might look unnaturally tall and skinny or short and wide. Our calculator does the math for you to ensure this distortion doesn’t happen.
Can I use this calculator for printing photos?
Absolutely. Let’s say your camera takes photos with a 3:2 aspect ratio (e.g., 6000×4000 pixels), and you want to print a standard 8×10 inch photo. The aspect ratio of an 8×10 is 5:4 (or 10/8 = 1.25). This is different from your camera’s 3:2 ratio (3/2 = 1.5). This means you will have to crop some of the original image to make it fit the 8×10 paper without distortion. You can use our calculator to determine how to crop.
Example: To fit your 6000×4000 photo into an 8×10 frame, you’ll need to crop it. If you keep the height at 4000 pixels, the new width would need to be (4000 / 10) * 8 = 3200 pixels. You would have to crop the sides of your original 6000px wide photo to fit this new 3200×4000 dimension.
What is an anamorphic aspect ratio?
Anamorphic is a filmmaking technique where a wide image is “squeezed” horizontally onto a standard film frame using a special lens. During projection, a corresponding lens “de-squeezes” the image back to its original ultrawide aspect ratio (often 2.39:1). This method was historically used to create a widescreen image without using wider film stock. You see its signature lens flares in many modern blockbuster movies.
Does aspect ratio affect file size?
Not directly. File size is determined by the total number of pixels (resolution) and the compression used, not the ratio itself. However, a video with a larger aspect ratio on the same screen (e.g., 21:9 vs 16:9) will have more pixels if it fills the screen horizontally, which can lead to a larger file size. But a 1920×822 (21:9) video actually has fewer pixels than a 1920×1080 (16:9) video, and would thus have a smaller file size, all else being equal.
What’s the difference between 16:9 and 9:16?
They are the inverse of each other.
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16:9 is a horizontal (landscape) rectangle, wider than it is tall. This is the standard for TVs and computer screens.
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9:16 is a vertical (portrait) rectangle, taller than it is wide. This is the standard for smartphone screens and social media stories.
How do I fix an image that is already stretched?
Unfortunately, you can’t truly “fix” it by adding back the lost data. Once an image is saved with the wrong aspect ratio, the original pixel information is gone. The best solution is to find the original, undistorted image and resize it correctly using a tool like this calculator. If you don’t have the original, you can try to guess the intended aspect ratio and resize it, but it will likely result in a loss of quality.
After you’ve determined the correct dimensions, you might want to calculate how that impacts file size for uploading or storage. Check out our Video File Size Calculator to estimate the final size of your video. If you’re working with prints, use our DPI/PPI Calculator to ensure your image resolution is high enough for a quality print.
