The prewean period is one of the most important stages of dairy calf development. A tool is needed to more accurately assess calf growth, specifically muscle development. The objective was to determine if ultrasound can be used to predict longissimus dorsi (ribeye) linear depth and external carpi radialis (front) and semitendinosus (hind) area in postmortem preweaned Holstein calves. Postmortem bull and heifer calves (n = 191, age 17.3 ± 20.67 d, body weight 37.9 ± 19.07 kg) were obtained from 2 calf ranches between April and July 2013. Ultrasound images of the ribeye, front, and hind muscles were collected using an Aloka 500V equipped with a 5-cm 7.5-MHz linear transducer. Ultrasound ribeye linear depth and front and hind areas were calculated using the Ultrasound Image Capture System. The ribeye was dissected and measured for linear depth. The front and hind muscles were dissected and the cross-sectional planes were traced onto transparency paper. The transparency paper was photocopied and individual paper muscle tracings were cut out and weighed. The weights of the paper muscle tracings were then converted to areas using the known area of a standard 8.5 × 11 inch paper. Means were calculated using PROC GLM in SAS (version 9.2). Mean dissected values for the ribeye, front, and hind muscles (1.65 ± 0.44 cm, 6.23 ± 1.83 cm², 9.05 ± 2.37 cm²) were greater than the respective mean ultrasound values (1.46 ± 0.37 cm, 5.41 ± 1.49 cm², 8.60 ± 2.40 cm²) indicating ultrasound underestimated the true linear depth and area values consistently. The relationship between the dissected and ultrasound measurements was tested using Pearson correlation coefficient (PROC CORR). Overall, there was a strong, positive relationship between both the dissected and ultrasound measurements for the ribeye (r = 0.55, P < 0.01), front (r = 0.65, P < 0.01), and hind muscle (r = 0.80, P < 0.01). The weight, age, and sex of the calf and the operator of the ultrasound may explain some of the variability not accounted for by the correlation coefficient. The semitendinosus muscle displayed the highest correlation coefficient and may be used in future studies to assess calf muscle growth and guide implementation of dynamic feeding changes on both dairy farms and calf ranches.