A computerized bone age assessment requires segmentation of the X-ray carpal bones from other undesired tissue regions. This paper presents segmentation and area measurement of carpal bones in X-ray images. The locally weighted K-means variational level set was applied in segmenting 67 X-ray carpal bone datasets. Dice coefficient and Hausdorff distance measures show mean values above 0.7 and around 3 pixels, respectively. These satisfying segmentation outcomes enable the carpal bone areas to be measured on the segmented images. The carpal bone area measurement ranged from 4.24 mm to 48.96 mm with a mean value of 20.70 ± 10.51 mm and various values of the Pearson’s correlation coefficient implies that the segmentation method is insensitive to different carpal bone areas and locations. These results suggest that the methods can be applied in the bone age assessment by quantifying changes in the carpal bone area over certain time intervals.