T​he Breed Standard
The Labrador Retriever breed stnadard has been defined as:

General Appearance
Strongly built, short coupled, very active; broad in skull, broad and deep through chest and ribs; broad and strong over loins and hindquarters.

Characteristics
Good tempered, very agile (which precludes excessive body weight or excessive substance). Excellent nose, soft mouth; keen love of water. Adaptable, devoted companion.

Temperament
Intelligent, keen and biddable, with a strong will to please. Kindly nature, with no trace of aggression or undue shyness. 

Head and Skull
Skull broad with defined stop; Clean cut without fleshy cheeks. Jaws of medium length, powerful, not snipey. Nose wide, nostrils well developed.

Eyes
Medium size, expressing intelligence and good temper; brown or hazel.

Ears:
Not large or heavy, hanging close to head and set rather far back. 

Mouth
Jaws and teeth strong, with a perfect and regular complete scissor bite, ie. the upper teeth closely overlapping the lower teeth and set square to the jaws.

Neck
Clean, strong, powerful, set into well-placed shoulders. 

Forequarters
Shoulders long and sloping. Forelegs well-boned and straight from elbow to ground when viewed from either front or side.

Body
Chest of good width and depth, with well-sprung barrel ribs - this effect not to be produced by carrying excessive weight.  Level topline. Loins wide, short coupled and strong. 

Hindquarters
Well-developed, not sloping to tail; well turned stifle. Hocks well let down, cow-hocks highly undesirable. 

Feet
Round, compact; well-arched toes and well developed pads. 

Tail
Distinctive feature, very thick towards base, gradually tapering towards tip. Medium length, free from feathering, but clothed thickly all around with short, thick, dense coat, thus giving "rounded" appearance described as "Otter" tail. May be carried gaily, but should not curl over back.

Gait/Movement
Free, covering adequate ground; straight and true in front and rear.

Coat
Distinctive feature, short, dense, without wave or feathering, giving fairly hard feel to the touch; weather resistant undercoat. 

Colour
Wholly black, yellow or liver / chocolate, yellow range from light cream to red fox. Small white spot on chest permissible. 

Size
Ideal height at withers: 
Dogs 56 - 57cms (22 – 22½'')   -   Bitches 54 - 56cms (21½ - 22")

Faults
Any departure from the foregoing points should be considered a fault and the seriousness with which the fault should be regarded is in exact proportion to its degree and its effect on the health and welfare of the dog and on the dog's ability to perform its traditional work.

Note
Male animals should have two apparently normal testicles fully descended into the scrotum. 

Reprinted with permission of the Kennel Club