Aspect ratio = width : height, reduced by their greatest common divisorHow to use this calculator
- Enter the original pixel width and height, or choose a common creative preset.
- Read the simplified ratio and check the visual frame preview.
- Choose a new width or height. Copy the paired dimensions for your design or editing tool.
Worked example
A 1920 × 1080 video reduces to a 16:9 ratio. Setting a new width of 1280 gives a height of 720. A 1080 × 1920 vertical video is 9:16, not 16:9: width is always written first.
Aspect ratio and resolution describe different things
Aspect ratio is the shape of the frame; resolution is the number of pixels. Both 1920 × 1080 and 1280 × 720 have a 16:9 shape, but they contain different amounts of image information. Increasing pixel dimensions does not recover detail absent from the source.
Common ad creative shapes
The presets offer square 1:1, portrait 4:5, vertical 9:16 and landscape 16:9 working canvases. A shape alone does not prove eligibility for every ad placement. Confirm the platform’s current size, format and placement rules, then check the final creative in a preview.
Resizing, cropping and padding
Scaling both dimensions proportionally preserves the frame shape. Cropping changes the visible content to fit a different shape; padding adds space around it. This calculator provides dimensions only. It does not edit your file or stretch an image to a different aspect ratio.
Reference: YouTube: video resolution and aspect ratios.
Common questions
How do I calculate an image aspect ratio?
Divide the width and height by their greatest common divisor. For 1920 × 1080, divide both by 120 to get 16:9. Use the original pixel dimensions, not a screenshot of an image displayed inside another layout.
What is the difference between 9:16 and 16:9?
9:16 is portrait, with height greater than width. 16:9 is landscape, with width greater than height. The order matters because aspect ratios are expressed as width to height.
Why does my result look unusual, such as 300:157?
The calculator shows the exact reduced ratio. A 1200 × 628 image is exactly 300:157, which is approximately 1.91:1. A commonly rounded label and an exact pixel ratio need not be identical.
Will it resize or compress my image or video?
No. It calculates dimensions to use in your editor. No file upload or media conversion is required. When a proportional dimension is not a whole pixel, the tool rounds to the nearest pixel and tells you.