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calcthai.com · Image Aspect Ratio and Resize Calculator
General & conversion
Image Aspect Ratio and Resize Calculator
Find an image’s simplified ratio and the height for a new width. See exact and rounded dimensions, scale and megapixels without uploading an image.
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Find an image’s simplified ratio and the height for a new width. See exact and rounded dimensions, scale and megapixels without uploading an image.
How it works
New height = old height × new width / old width, rounded to the nearest whole pixel with a minimum of one. Divide original width and height by their greatest common divisor for the simplest ratio. Megapixels = width × height / 1,000,000.
Example: 1,920 × 1,080 simplifies to 16:9. A width of 1,280 gives a height of 720, a 66.67% scale and approximately 0.92 megapixels.
This calculates dimensions only; it does not edit a file or add detail when upscaling. Pixel rounding can slightly change the ratio, especially for very small images.
Frequently asked questions
How can I resize by height instead?
Swap the original width and height, then enter the desired height as the new width. The returned height becomes the required width.
Does this determine print quality?
It gives pixel proportions. Print dimensions and quality also depend on DPI and the original image.
Sources
Method last verified 19 Sep 2026