Boxer coat colors are relatively simple. The American Kennel Club standard lists two colors, fawn and brindle. White markings are common; white may cover the entire body. All purebred boxers have a black mask on the muzzle, though it may be partially or fully covered by white markings.
Fawn
Fawn is a solid color, ranging from a light tan to a dark reddish hue. The darker fawns are sometimes referred to as mahogany or deer-red in color -- in fact in some countries, the term "red" is used instead of fawn to describe the color. Darker fawns may have some black hairs interspersed in their coat, or the fawn hairs may be tipped with black. This may create small black areas or "smudging" on parts of the coat, especially the edges of the ears.
Brindle
The other color in the AKC boxer standard is brindle, which is black striping on the fawn base coat. Technically speaking, all boxers are fawn -- brindle is a marking pattern rather than an actual color. It's much easier to call brindle a color, however, and that convention has worked well for a century. Brindle boxers can have just a few stripes on their fawn body -- sometimes jokingly called "frindles." On the other end of the spectrum, the stripes can be heavy enough to, as the American Kennel Club standard describes, "create the appearance of reverse brindling," since it looks like fawn stripes are painted on a black body. The fawn base color should always be visible, however, even if on just a few small areas on the body.
White
White is another marking pattern -- genetically, all white boxers are either fawn or brindle underneath the white "paint job." The amount of white markings can vary considerably, from none to 100 percent coverage. Boxers with white markings that cover one-third or less of the body are called "flashy." These markings are typically found on the feet, legs, neck and face. When most of the body is white, the dog is called a white boxer -- again not technically correct, but it's easier that way. White boxers often have patches of color, typically on the ears or around the eyes and occasionally on the back. The AKC provides registration codes for both white markings and white as a color.
White boxers are not rare or unusual; while official statistics haven't been kept, a reasonable estimate is that about 20 percent of all boxers are white. Dogs with white covering more than one-third of their bodies are disqualified from dog shows by the breed standard and are prohibited from breeding by the parent club code of ethics. White boxers can participate in obedience, agility, herding, coursing, rally and other activities.
Genetics
The genetics of boxer coat colors are straightforward. Brindle is dominant to fawn, which means a dog with even one brindle gene will be brindle. Modifiers, rather than the brindle gene, determine the amount of brindle stripes on a boxer -- a dog with two brindle genes may or may not have more stripes than a dog with one brindle gene. White markings are caused by the extreme piebald gene and are co-dominant. A dog with one white gene will be flashy, while a dog with two white genes will be mostly or all white.
Black
A growing number of breeders are selling "black boxers," often marketed as "rare" and sold for high prices. Unfortunately, a black coat is genetically impossible for a boxer, and the AKC does not provide a color code for black. The only way to get a black coat is to cross a boxer with another breed. Since black is dominant to fawn and brindle, it cannot be "hidden" for generations; if the dog has one gene for black coat color, it will have a black coat.