What is aspect ratio?

Aspect ratio is the proportional relationship between an image's width and height, expressed as W:H in its simplest whole-number form. For example, a 1920×1080 image has an aspect ratio of 16:9.

How are ratios simplified?

The tool divides both dimensions by their greatest common divisor (GCD), which is computed using the Euclidean algorithm. This always yields the smallest equivalent whole-number ratio.

Can I calculate a missing dimension?

Yes. Switch to the "Find Dimension" mode, enter one known dimension and the desired ratio (e.g. width=1280, ratio=16:9), and the tool calculates the other dimension (height=720).

Image Aspect Ratio Calculator

Calculate the aspect ratio from width and height, or compute a missing dimension from a known ratio.

Width

Height

Aspect Ratio16:9

Common resolutions

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FAQ

What is aspect ratio?: Aspect ratio is the proportional relationship between an image's width and height, expressed as W:H in its simplest whole-number form. For example, a 1920×1080 image has an aspect ratio of 16:9.
How are ratios simplified?: The tool divides both dimensions by their greatest common divisor (GCD), which is computed using the Euclidean algorithm. This always yields the smallest equivalent whole-number ratio.
Can I calculate a missing dimension?: Yes. Switch to the "Find Dimension" mode, enter one known dimension and the desired ratio (e.g. width=1280, ratio=16:9), and the tool calculates the other dimension (height=720).

The Image Aspect Ratio Calculator has two modes. In the first mode, enter any width and height to see the simplified aspect ratio (e.g. 1920×1080 → 16:9). In the second mode, enter one dimension and an aspect ratio to calculate the other dimension. Ratios are simplified using the greatest common divisor algorithm. No image upload is required — this is a pure numeric calculator.