What is aspect ratio?
Aspect ratio describes the proportional relationship between width and height. A 16:9 image, for example, is 16 units wide for every 9 units high.
How to resize while keeping the same aspect ratio
When you change the width, the matching height can be calculated from the original dimensions. This prevents the image or video from becoming stretched or compressed.
Aspect ratio example
A 1920 × 1080 image resized to 1280 pixels wide should be 720 pixels high. Both sets of dimensions maintain the same 16:9 proportion.
Common aspect ratios
16:9
Common for widescreen video, televisions, monitors and online video.
4:3
Common in older displays, presentations and some photography.
1:1
A square format where width and height are equal.
9:16
A vertical format commonly used for mobile-first video and portrait content.
Changing width and height independently can distort an image. Keep the same aspect ratio when you want the original proportions to remain unchanged.
Frequently asked questions
How do I calculate an aspect ratio?
Compare width with height and reduce both values by their greatest common divisor when you want the simplified ratio.
What aspect ratio is 1920 × 1080?
1920 × 1080 uses the 16:9 aspect ratio.
What size is 16:9 at 1280 pixels wide?
The matching height is 720 pixels, producing dimensions of 1280 × 720.
Does changing resolution change aspect ratio?
Not if width and height are scaled proportionally. 1920 × 1080 and 1280 × 720 have different resolutions but the same ratio.