Size:
Height at withers about 10-1/2 inches (26 cm). Weight 23-25 lb. (10-11 kg) for dogs, bitches slightly less. Size is more important than weight. General conformation, overall balance, type and substance are the main criteria. Faults: Much oversized or undersized.

Coat and Colour:
Coat weather-resisting, comprised of a soft dense undercoat and hard, straight, wiry topcoat. Colour: All white or with lemon, tan, badger, or blue badger markings on head and ears. Heavy body markings and excessive undercoat ticking are to be discouraged. Faults: Silky or curly coat. Heavy body markings.

Head:
Long, broad, and powerful without coarseness. It should be in perfect balance with the body, joining the neck smoothly. Length of head roughly three-quarters height at withers. Breadth of skull a little less than half the length of head. Skull: very slightly domed and broad, with a shallow indentation running down between the brows, and joining the muzzle with a moderate stop. The planes of the skull from brow to occiput and the dorsal aspect of the muzzle should approximate a parallel rather than an angled aspect. Cheeks smoothly formed and flat without heavy jowls. Muzzle: Full and well-boned, of approximate equal length to the skull. Jaws and Teeth: Jaws powerful and square. Teeth strong and white; very large for size of dog and canines fitting closely together. Scissor bite preferred; level accepted. Nose: Black with large nostrils. Eyes: Dark, deeply set and fairly wide apart, of medium size and oval in shape with a keen terrier expression. The mature Sealyham should have some degree of eyelid pigmentation. Ears: Folded level with the top of the head, with the inner edge close to the cheek. Well rounded at tip, of length to reach the outer corner of the eye. Thin, not leathery, and of sufficient thickness to avoid vertical creases. Faults: Undershot or overshot bite. White, cherry or butterfly nose. Light, large or protruding eyes. Prick, tulip, rose or hound ears.

Neck:
Length slightly less than two-thirds of height at withers. Muscular without coarseness, with good reach, refinement at throat, set firmly on shoulders at the withers with a smooth curve.

Forequarters:
Shoulders well laid back and powerful but not over-muscled. Sufficiently wide to permit freedom of action. Forelegs should be short, strong with good bone, and as straight as is consistent with the chest being well let down between them. Elbows close to the body and forefeet straight ahead or slightly turned out. Forefeet large and round, yet compact with deep pads, arched toes and strong nails. Faults: Upright or straight shoulder placement. Out at elbow. Down on pasterns, knuckled over. Thin, spread or flat feet. Poor bone in forelegs.

Body:
Strong and substantial with well sprung ribs. Not too barrel-shaped, the ribs should be well rounded as they leave the spine and then flatten gradually to a deep chest. Topline level, neither roached nor swayed. Length from withers to set-on of tail should approximate height at withers or 10-1/2 inches (26 cm). Brisket deep and well let down between forelegs. Loin, croup and abdomen strong, short-coupled and substantial with great flexibility. Faults: Roached or sway back. Back too long or too short. Shallow chest.

Hindquarters:
Hind legs longer than forelegs and not so heavily boned. Hip bone protruding behind the set-on of tail to give a well-defined buttocks. Upper and lower thighs strong and powerful with stifles well bent. Hocks well let down and parallel to each other. Rear feet compact with deep pads, arched toes and strong nails but smaller and more oval than the forefeet. Faults: Weak hindquarters. Straight in stifle. Cow hocks.

Tail:
Docked and carried upright. Set on far enough forward so that the spine does not slope down to it. Faults: Low tail set.

Gait:
Action sound, strong, quick, free, true and level. Faults: Lack of drive in gait.

The foregoing description is that of the Sealyham Terrier. Any deviation from the above described dog must be penalized to the extent of the deviation, keeping in mind the original purpose of the breed.