Throughout this article, [RL] denotes the concentration of a receptor-ligand complex, [R] the concentration of free receptor, and [L] the concentration of free ligand (so that the total concentration of the receptor and ligand are [R]+[RL] and [L]+[RL], respectively). Let n be the number of binding sites for ligand on each receptor molecule, and let  represent the average number of ligands bound to a receptor. Let K denote the dissociation constant between the ligand and receptor. The Scatchard equation is given by
By plotting /[L] versus , the Scatchard plot shows that the slope equals to -1/K while the x-intercept equals the number of ligand binding sites n.