Aspect ratio
Also known as: photo aspect ratio, video aspect ratio, 16:9, 4:3
Aspect ratio is the proportional relationship between an image or video’s width and height, written as two numbers like 4:3 or 16:9. It shapes how a photo fills the frame and has a smaller effect on file size than resolution or quality.
- Width-to-height proportion, e.g. 4:3 or 16:9
- Describes shape, not pixel count
- Affects file size only through cropping
Common ratios
Phone cameras often default to 4:3 for stills and 16:9 for video. Square photos are 1:1, and many phones offer a tall 9:16 for full-screen vertical shots. The ratio describes shape, not the number of pixels.
Changing the ratio crops the frame rather than improving detail. A 16:9 photo simply trims the top and bottom of the sensor’s 4:3 view, so it can even contain slightly fewer pixels than the full-frame option.
Why it matters for storage
Aspect ratio affects file size only indirectly, through how many pixels remain after cropping. A wider crop discards some of the frame and can be marginally smaller, but resolution, format, and compression drive size far more.
For storage planning, focus on capture resolution and format rather than ratio. Choosing a ratio is mostly a composition decision about how the shot is framed.