4:3 is a ratio.

It is a commonly used image aspect ratio, where it refers to the ratio of an image's width to its height. It has been in use since television's origins and many computer monitors use the same aspect ratio. Since 4:3 is close to the old 1.37:1 cinema academy format, theaters suffered from a loss of viewers after films were broadcast on TV. To prevent this, Hollywood created widescreen aspect ratios to immerse the viewer in a more realistic experience and, possibly, to make broadcast films less enjoyable if watched on a regular TV set.

Aspect ratios compared

4:3 (1.33:1)	16:9 (1.78:1)

• 4:3 ratio is two of the minimum Pythagorean triple.
• The conventional television has the ratio of 4:3, while the HDTV has that of 16:9.

See also

• Aspect ratio (image)
• Display resolution
• 16:9

ja:アスペクト比