Size:
Equal consideration must be given to height, length of back and weight. Height at shoulder for either sex should be about 10 inches (25 cm). Generally, a well-balanced Scottish Terrier Dog of correct size should weigh from 19-22 lb. (9-10 kg), and a Bitch, from 18-21 lb. ( 8-9.5 kg). The principal objective must be symmetry and balance.

Coat and Colour:
Coat rather short, about 2 inches (5 cm), dense undercoat with outer coat intensely hard and wiry. Colour steel or iron grey, brindled or grizzled, black, sandy or wheaten. White markings are objectionable and can be allowed only on the chest and that to a slight extent only.

Head:
Skull long, of medium width, slightly domed and covered with short, hard hair. It should not be quite flat, as there should be a slight stop or drop between the eyes. Muzzle in proportion to the length of skull, with not too much taper towards the nose. Nose should be black and of good size. The jaws should be level and square. The nose projects somewhat over the mouth, giving the impression that the upper jaw is longer than the lower. The teeth should be evenly placed, having a scissors or level bite, with the former being preferable. Eyes set wide apart, small and of almond shape, not round. Colour to be dark brown or nearly black. To be bright, piercing, and set well under the brow. Ears small, prick, set well up on the skull, rather pointed but not cut. The hair on them should be short and velvety.

Neck:
Moderately short, thick and muscular, strongly set on sloping shoulders, but not so short as to appear clumsy.

Forequarters:
Shoulders sloping. Both forelegs and hind legs should be short and very heavy in bone in proportion to the size of the dog. Forelegs straight or slightly bent with elbows close to the body. Scottish Terriers should not be out at the elbows.

Body
Moderately short and well ribbed up, chest broad and very deep, well let down between the forelegs. Loin strong, flanks deep.

Hindquarters:
Very muscular. Stifles should be well bent and legs straight from hock to heel. Thighs very muscular. Feet round and thick with strong nails, forefeet larger than the hind feet.

Tail:
Never cut and about 7 inches (18 cm) long, carried with a slight curve but not over the back.

Gait:
The gait of the Scottish Terrier is peculiarly its own and is very characteristic of the breed. It is not the square trot or walk that is desirable in the long-legged breeds. The forelegs do not move in exact parallel planes - rather in reaching out incline slightly inward. This is due to the shortness of leg and width of chest. The action of the rear legs should be square and true and at the trot both the hocks and stifles should be flexed with a vigorous motion.

Faults:
Soft coat, round or very light eye, overshot or undershot jaw, obviously oversize or undersize, shyness, timidity, or failure to show with head and tail up are faults to be penalized. No judge should put to Winners or Best of Breed any Scottish Terrier not showing real terrier character in ring.