There are several methods to calculate QCD scattering information on the lattice, but one of the most popular methods is the Lüscher formalism. In this talk, I will discuss how we use the finite-volume energy spectrum and the Lüscher formalism to calculate infinite-volume scattering results, and how it may require non-intuitive methods. Using $N_f=2+1$ lattice QCD for pion masses near 200 MeV, a summary of the $\Delta$ resonance calculation is reviewed, as well as quick looks at the $K_0^\ast(700)$, $a_0(980)$, deuteron, and dineutron scattering channels.
Andrew Hanlon