http://www.homebuildingandrepairs.com Click on this link link for more information about stair building, remodeling and design. This video will provide you with easy to understand step-by-step instructions that can be used to figure out or calculate the length of a stair stringer. This information is often helpful when estimating the length of materials that need to be purchased to build the stairway. Contractors and do-it-yourselfers can both benefit from simple and easy to understand mathematical formulas like this one.