Aspect Ratio Calculator | Resize Width and Height
Calculate proportional width or height for images, videos, thumbnails, and layouts without stretching the original aspect ratio.
Original Dimensions
Current Aspect Ratio
New Dimensions
Resize Without Distorting Aspect Ratio
Enter an original width and height, then change one dimension to calculate the matching proportional size for images, videos, thumbnails, or embeds.
Use Common Ratios for Visual Platforms
Compare 1:1, 4:3, 16:9, 9:16, and other ratios before cropping or resizing so the final asset fits the target layout.
When Aspect Ratio Math Helps
Use it for YouTube thumbnails, social posts, product images, hero sections, video embeds, slides, and responsive design assets.
Overview
Aspect Ratio Calculator finds the proportional relationship between width and height for any dimensions, calculates the missing dimension when one side is known, and converts between common ratios like 16:9, 4:3, and 1:1.
Typical Use Cases
Use this when resizing an image or video and you need to maintain proportions, or when building a responsive layout and you need the height for a given width at a fixed ratio.
How to Use
- Enter the original width and height.
- Enter the new width or height you want to scale to.
- Click Calculate to find the missing dimension.
- Switch modes to find the ratio from any two dimensions.
Common Questions
What is a 16:9 aspect ratio?
16:9 is the widescreen standard used by HD televisions, YouTube, and most monitors. The width is 16 units for every 9 units of height.
How do I keep aspect ratio when resizing?
Divide the new width by the original width to get a scale factor, then multiply the original height by that same factor.
What aspect ratio should I use for Instagram?
Instagram supports 1:1 square, 4:5 portrait, and 1.91:1 landscape. The 4:5 portrait takes up the most feed space on mobile.
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