Medication errors are among the most common life-threatening mistakes made in health care. The ability to accurately calculate drug doses, especially in intensive care units (ICUs), where the majority of medications are infused, reduces medication errors. Researchers have proposed dimensional analysis to improve mathematical calculations of drugs. This study was conducted to determine the effects of dimensional analysis on the infusible medication calculation skills among nursing students in ICUs. In this quasi-experimental study, the research samples consisted of sixth-semester nursing students who were assigned to an intervention group (n = 34) and a control group (n = 32). For the intervention group, the calculations of common infusible drugs in the ICU were taught using the dimensional analysis method, whereas the control group received training without the dimensional analysis method. Data collection instruments included a demographic characteristics questionnaire and a 10-item questionnaire of drug calculations that were measured before and after the intervention in both groups. Data analysis was performed using SPSS 22 . The mean pretest scores for infusible drug calculations of nursing students in the ICU were 5.15 ± 2.35 for the intervention group and 5.25 ± 2.56 for the control group ( P = .86). The mean posttest scores of the intervention group and control group were 9.22 ± 0.79 and 6.27 ± 1.87, respectively ( P = .0001). Dimensional analysis training significantly improved the infusible medication calculation skills of nursing students in the ICU. It is recommended to include this method in undergraduate, graduate, and continuing education nursing courses to increase skills in calculating infusible drugs and to reduce medication errors.