Height measurement in the critical care unit is necessary for estimating ideal body weight and providing titrated patient care. In this study, we compare three methods of height assessment and evaluate their level of correlation and inter-observer reproducibility. Heights of 100 consecutive patients were assessed independently by two nurses by supine, four point, and arm span methods. Paired sample t-test, one-way analysis of variance, Tukey′s honestly significant difference post-hoc analysis and Bland-Altman plots were performed to assess agreement between measurements. Arm span method showed higher mean height compared to supine and four point methods. Mean heights derived by supine and four point measurements were similar to each other but were significantly different from that of arm span method (P < 0.001). Inter-observer correlation of the measured heights was very good among all three methods. The supine method seems to be easy, accurate, and reproducible in our study.