Technology
Image Aspect Ratio Calculator
Work out a proportional height or width for an image, or simplify its aspect ratio, from two known dimensions.
px
px
px
Your results
New height720 px
Simplified aspect ratio16:9
Calculation breakdown
- Proportional height
- new width × (original height ÷ original width)
- Simplified ratio
- width ÷ GCD : height ÷ GCD
Worked example
Resizing a 1920x1080 image to a width of 1280 px gives a proportional height of 720 px, keeping the 16:9 ratio.
Assumptions
- Assumes uniform scaling with no cropping.
- Height is rounded to the nearest whole pixel.
How this calculator works
Enter an original width and height plus a new width to get the proportional new height (or vice versa), and see the simplified aspect ratio such as 16:9 or 4:3.
Frequently asked questions
How is the simplified ratio found?
The width and height are divided by their greatest common divisor to give the smallest whole-number ratio, such as 16:9.
Can I resize by height instead of width?
Yes, use the resize-by-height mode to keep the same proportions when only the target height is known.
Why keep the aspect ratio the same?
Changing width and height by different factors distorts the image, stretching or squashing the content.
Related calculators
Screen Resolution Megapixel CalculatorCalculate the total megapixel count and aspect ratio of a screen resolution such as 1920x1080 or 3840x2160.Screen Pixels Per Inch (PPI) CalculatorCalculate a screen's pixel density (PPI) from its resolution and diagonal size in inches.Video File Size CalculatorEstimate the file size of a video from its bitrate and duration, useful for storage and upload planning.Unit Conversion CalculatorConvert length, weight, volume, area, temperature, speed and fuel economy units, including litres per 100km, km per litre and miles per gallon.Video Bitrate CalculatorCalculate the recommended video bitrate to hit a target file size, or the resulting size from a chosen bitrate.