Coloration of red foxes ranges from pale yellowish red to deep reddish brown on the upper parts and white, ashy or slaty on the underside. The lower part of the legs is usually black and the tail usually has a white or black tip. Two color variants commonly occur. Cross foxes have reddish brown fur with a black stripe down the back and another across the shoulders. Silver foxes range from strong silver to nearly black and are the most prized by furriers. These variants are about 25% and 10% of red fox individuals, respectively. Red foxes, like many other canid species, have tail glands. In Vulpes vulpes this gland is located 75 mm above the root of the tail on its upper surface and lies within the dermis and subcutaneous tissue. The eyes of mature animals are yellow. The nose is dark brown or black. The dental formula is 3/3 1/1 4/4 2/3. The tooth row is more than half the length of the skull. The premolars are simple and pointed, with the exception of upper fourth premolars, the carnassials. Molar structure emphasizes crushing. The manus has 5 claws and the pes 4 claws. The first digit, or dew claw, is rudimentary but clawed and does not contact the ground.
Red foxes are the largest of the Vulpes species. Head and body length ranges from 455 to 900 mm, tail length from 300 to 555 mm, and weight from 3 to 14 kg. Males are slightly larger than females. Populations in southern deserts and in North America are smaller than European populations. Body mass and length among populations also varies with latitude (being larger in the north, according to Bergmann's rule).
Range mass: 3 to 14 kg.
Range length: 455 to 900 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Average basal metabolic rate: 13.731 W.