At maturity (over 18 months of age), the AKC standard recommends 27-30 inches for males with the desired height between 27 and 29 inches and 26 and 29 inches for females with the desired height between 26 and 28 inches. A mature male less than 27 inches or more than 30 inches at the withers is considered a serious fault. A mature female less than 26 inches or more than 29 inches at the withers is considered a serious fault. Although the standard also states 'Height consideration should not outweigh that of type, proportion, movement and other functional attributes.' In proportions, a Black Russian Terrier should be slightly longer than tall, a ratio of 9 ½ to 10 being ideal.