Aspect Ratio Calculator

1920:1080 = 16:9.

How it works

• Reduced the 1920:1080 pair by its greatest common divisor to 16:9.
• Kept the decimal ratio (width ÷ height) to 12 significant digits.
• Returned the simplified pair.

1920:1080 = 16:9

• The ratio is invariant under scaling, so every step keeps the same shape.

Methodology

1. Take the greatest common divisor of the two dimensions (scaling non-integers by 1000 first).
2. Divide both sides by that divisor to obtain the lowest integer ratio.
3. Report the decimal ratio as width ÷ height.
4. For resolve and scale modes, multiply or cross-multiply by the single proportional factor and round to 12 significant digits.

Usage

1. Choose whether to simplify, scale or resolve a missing dimension.
2. Enter the current width and height.
3. For scaling enter a factor; for resolving enter the new width or height.
4. Read the simplified ratio and the resulting dimensions.

Examples

These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.

Simplify 1920×1080

{
  "mode": "simplify",
  "width": 1920,
  "height": 1080
}

Double 1920×1080

{
  "mode": "scale",
  "width": 1920,
  "height": 1080,
  "factor": 2
}

1920×1080 resized to a 1280 width

{
  "mode": "resolve-width",
  "width": 1920,
  "height": 1080,
  "newValue": 1280
}

1920×1080 resized to a 720 height

{
  "mode": "resolve-height",
  "width": 1920,
  "height": 1080,
  "newValue": 720
}

Limitations

One ratio, many sizes

An aspect ratio is the proportional relationship between width and height; 1920×1080, 1280×720 and 640×360 are all 16:9 because each dimension is multiplied by the same factor.

Reducing by the greatest common divisor is what turns a specific pixel size into the canonical ratio you see quoted for displays, photos and video.