16:9 and 4:3 aspect ratios

16:9 is an aspect ratio with a width of 16 units and height of 9. Since 2009, it has become the most common aspect ratio for sold televisions and computer monitors and is also the international standard format of HDTV, Full HD, non HD television and analog widescreen television. 

A 4:3 aspect ratio will produce more box-like picture, because the screen is only slightly wider than it is high. 4:3 means for every 4 units of width in an image, it will have 3 units of height. it mathematical terms it comes like width is 33% higher than it is high. the 4:3 aspect ratio has been around since early days of television back to 1940’s and 50s. A television that has an aspect ratio of 4:3 is often referred as being NTSC, or pan and scan. The majority of cable channels still broadcast in 4:3 

There are a few aspect ratio calculators and below table gives the height and width some of the applications can use that an preserve the 16:9 aspect ratio. 

320x180(16:9)   

320x240 (4:3)

352x19816:9)   

352x264(4:3)

there is a nice calculator available to do this easily and the links are below 

http://size43.com/jqueryVideoTool.html 

http://size43.com/jqueryVideoTool-4x3.html

References

http://www.steves-digicams.com/knowledge-center/how-tos/digital-camera-operation/the-difference-between-a-169-aspect-ratio-and-43-aspect-ratio.html#b