Aspect Ratio Calculator
Aspect Ratio Calculator - a browser-based image tools utility.
Browser tool
About Aspect Ratio Calculator
Working out the second dimension when you know the first and the ratio, so an image or a video scales without being stretched. It is simple arithmetic that is easy to get wrong in a hurry and immediately visible when you do. A free online calculator that asks you to sign up for nothing. There is no file to upload here at all, and the numbers you type stay where you typed them.
How to use it
- Choose or enter the ratio16:9, 4:3 and 1:1 are one click; any other pair of numbers can be typed in directly.
- Enter the dimension you knowWidth or height. The other is calculated.
- Round sensiblyExact ratios rarely give whole pixels. Rounding by one pixel is invisible; ignoring the ratio is not.
Why a stretched image is so obvious
Human vision is acutely sensitive to distortion in faces and circles. A five percent error in aspect ratio is imperceptible on an abstract pattern and immediately wrong on a photograph of a person — which is why "it looks a bit off" is so often a ratio mistake rather than anything to do with colour or sharpness.
What it does not do
- This gives dimensions. Whether the content should be cropped or letterboxed to reach them is an editorial decision it cannot make.
- Pixel dimensions must be whole numbers, so an exact ratio is sometimes unattainable and the nearest whole pixel is the right answer.
Questions people ask
- What height should a 16:9 video be at 1920 wide?
- 1080. The ratio divides 1920 by 16 to get 120, then multiplies by 9. The same arithmetic gives 720 for a 1280-wide frame.
- Should I crop or letterbox to change ratio?
- Crop when the subject allows it and the edges are expendable; letterbox when nothing can be lost. Stretching to fit is the one option that is always wrong, because it distorts everything in the frame.
Questions about ToolsVerse itself — privacy, cost, what happens to your files — are answered in the frequently asked questions.
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