The most reliable way to tell a male cat from a female is by looking at the space and shape of the openings beneath the tail. This works on cats of any age, from newborn kittens to adults, and takes only a few seconds once you know what to look for.
The Genital Area: What to Look For
Gently lift the cat’s tail to expose two openings. The one directly under the tail is the anus. Below it is the genital opening, and this is where the key differences appear.
In females, the genital opening is a vertical slit sitting close to the anus. The two openings together resemble a lowercase “i” or an upside-down exclamation point, with very little space between them.
In males, the genital opening is a small round dot, and it sits noticeably farther from the anus. In intact (unneutered) males, you’ll also see the scrotum between the two openings, which looks like two small bumps. In neutered males, the scrotum may be less visible but the extra distance between the anus and the round genital opening is still apparent. Think of the male arrangement as a colon (:) and the female arrangement as a semicolon (;).
Sexing Kittens Under 8 Weeks
Young kittens can be harder to sex because everything is small and the testicles haven’t descended yet. The same two clues still apply: shape of the genital opening and distance from the anus. In kittens of similar size, males consistently have a greater gap between the two openings. If you’re examining a litter, comparing siblings side by side makes the difference much easier to spot.
Keep handling sessions brief. Kittens under a week old lose body heat quickly, so limit inspection to a minute or two and return them to their mother. Warm your hands first, and avoid handling kittens if the mother cat seems distressed.
How to Handle a Cat Safely for Checking
A calm cat will usually let you lift its tail without much fuss. If the cat is unfamiliar or nervous, start by offering the back of your hand for a sniff. For squirmy cats, a “taco hold” works well: fold the sides of a soft cat bed or towel around the cat’s body, leaving the rear end accessible. This keeps the cat feeling secure and protects you from scratches. A second person to gently hold the tail up while you look can make the whole process easier.
Coat Color as a Clue
Certain coat colors are strongly linked to sex because the gene controlling orange fur sits on the X chromosome. Since females have two X chromosomes, they can carry both orange and non-orange fur genes at the same time. This produces tortoiseshell (black and orange patches) and calico (black, orange, and white) patterns. Nearly all tortoiseshell and calico cats are female. A male would need an extremely rare extra X chromosome (XXY) to display those patterns.
Orange tabby cats lean male. Roughly three out of every four orange tabbies are male, because a male only needs one copy of the orange gene (on his single X chromosome) to be fully orange, while a female needs two copies.
Body and Face Differences in Adults
Intact adult males tend to be larger and more muscular than females of the same breed. The most distinctive feature is “tomcat jowls,” the thick, rounded cheeks that develop on unneutered males over time. These are caused by testosterone driving fat buildup and muscle thickening in the jaw and face. The longer a male stays intact, the more pronounced the jowls become. Neutered males and all females lack this look.
These body differences disappear as a clue in cats neutered before puberty, since testosterone levels drop before the secondary traits develop. A neutered male and a spayed female of the same breed can look nearly identical in body shape.
Behavioral Hints
Intact males spray urine on vertical surfaces to mark territory, and the smell is strong and unmistakable. They also roam farther, fight more, and are generally more restless than females. Intact females in heat vocalize loudly, sometimes for days, and adopt a distinctive posture with their hindquarters raised.
These behaviors are less useful for identifying neutered or spayed cats. Neutering reduces roaming and spraying significantly, though research has found that males neutered before puberty still spray and fight somewhat more than females neutered at the same age. So a slight behavioral lean can persist, but it’s not reliable enough to sex a cat on its own.
Checking for Spay or Neuter Signs
If you’ve found or adopted a cat and aren’t sure whether it’s been sterilized, look for a few common markers. Spayed females often have a small green tattoo on or near their belly incision. Neutered males may have a similar tattoo on the lower abdomen. Green is used in about 97% of cases. Feral cats that have been through trap-neuter-return programs typically have the tip of one ear surgically removed, a universal signal visible from a distance. If a male cat has no visible or palpable testicles but also no tattoo or ear tip, a vet can confirm neuter status with a quick exam or hormone test.
Knowing your cat’s sex early matters most for scheduling spay or neuter surgery and for separating males and females in multi-cat households before they reach sexual maturity, which can happen as early as four to five months of age.