I have do some real-world hands on testing videos on the iPad 3. After several conversions and tests I worked out the best settings for converting videos to iPad 3:
Resolution- 1920×1080 (Full HD)
Sampling rate- 48khz
So most users also want to keep the movies' quality as well as original. Please remember the file size is based more on bitrate than resolution, this isvery important. In order to keep the balance between file size and video quality, the 1080p with 1500~2000kbps is just all right. If you're care about the video quality more than the size, you can turn up the birate cause bitrate higher results in big file size, and lower visible quality loss. If you have any questions when watching videos on your iPad 3 or iPad 2, you can check out movie-entertainment tricks, tips, apps, tools for iPad 3 & iPad 2 at pavtube.com/enjoy-video-on-ipad-3.html to explore your options.