There are some hoary span charts out there (the old Western Woods Use Book comes to mind), but they are typically not that useful. Given the multiplicity of timber sizes, species and grades, along with variable lengths, spacings and loads, there are just too many different situations to cover in a table.

However there are a number of affordable and simple computer programs which do the job spreadsheet fashion. Names like BeamChek, BeamCalc and StruCalc come to mind. Check on the Net for more further information. And perhaps this note might provoke some reviews from users of these programs.