The Ag PhD Drainage Tile Calculator helps you determine your tile supply and capabilities for your field drainage project. You can calculate acres drained for single wall and dual wall tile in any size and grade, the pipe size needed to effectively drain acres, and the length of pipe you will need to purchase to complete your project. From Ag PhD - Information for Agriculture. For more agriculture and farm info, watch Ag PhD TV weekly with hosts Brian and Darren Hefty.