The present study investigated the influence of archwire size and ligation method on the force magnitude delivered by nickel-titanium alloy archwires to 4 incisor brackets (42, 41, 31, and 32) in a simulation of mandibular right lateral incisor linguoversion. The force delivered by 0.014 and 0.016 inch nickel-titanium alloy archwires was measured using a newly developed multi-sensor measuring system and the mean force magnitudes were compared between different archwire sizes when using conventional ligation (CL) with elastic modules or self-ligating (SL) brackets by three-way ANOVA and post-hoc Bonferroni’s tests. The mean force magnitudes for the brackets were significantly decreased in the order of 42, 41, 31, and 32 (p<0.01). The force magnitude was significantly larger in CL than SL at 42, 31, and 32 (p<0.05). In conclusion, the ligation method affected the force magnitude at 4 incisor brackets. Despite the ligation method, archwire size affected the force magnitude from 42 to 31.