A male kitten’s genital area looks like two small circular openings stacked vertically beneath the tail, with a noticeable gap of fur between them. The top opening is the anus, and the bottom one is the genital opening, which appears round. If you’ve heard the shorthand “female equals line, male equals circle,” that’s the simplest way to remember it. The difference is subtle in very young kittens but becomes easier to spot as they grow.
The “Colon” Shape in Males
When you gently lift a male kitten’s tail, you’ll see two openings arranged vertically. Both the anus (on top, just below the tail) and the genital opening (below it) are round. Together, they look like a colon punctuation mark ( : ). In female kittens, the genital opening is a vertical slit or teardrop shape instead of a circle, making the two openings together resemble a semicolon ( ; ).
The other major clue is spacing. Male kittens have a larger gap between the anus and the genital opening compared to females. That extra space, roughly half an inch or more even in newborns, is where the testicles will eventually develop. You’ll often see a small raised area or a bit of extra fur and skin in that space. In female kittens, the two openings sit much closer together with minimal fur between them.
What You’ll See at Different Ages
In newborns, both male and female kittens look remarkably similar, and even experienced breeders sometimes get it wrong. At birth, the testicles haven’t descended yet, so there’s no visible scrotum. The only reliable markers are the round shape of the genital opening and the wider spacing between the two openings.
By about two months of age, the testicles typically descend from inside the abdomen into the scrotum. At this point, you may notice two small, pea-sized bumps between the anus and the genital opening. This makes sexing much more straightforward. Some kittens take longer for the testicles to descend, but it rarely happens after six months. If you can’t feel or see them by two to four months, a vet can check for a retained testicle, a condition called cryptorchidism.
Between 8 and 16 weeks, the testicles become easy to feel by gently palpating the area between the two openings. By this age, there’s little ambiguity about whether you’re looking at a male or female kitten.
How to Safely Check
The best time to look is when the kitten is calm and warm. Cold, stressed kittens tend to squirm, and the area can be harder to see when muscles tense up. Place the kitten belly-down on a warm towel or soft surface and gently lift the tail. You don’t need to press, squeeze, or manipulate anything. A quick visual check is all it takes.
Avoid holding very young kittens away from their mother for more than a minute or two. Their body temperature drops quickly, and prolonged handling in the first week can be stressful. If you’re checking a litter, work through them one at a time and return each kitten to the nest before picking up the next.
Why Kittens Get Mis-Sexed
Mis-sexing kittens is extremely common, especially before six weeks of age. The most frequent mistake is identifying a male kitten as female because the testicles haven’t descended yet and the genital opening can look ambiguous. Without the visible bumps of the scrotum, people focus only on the shape of the opening, which can be hard to distinguish in a tiny, wiggly kitten.
Comparing littermates side by side is one of the most reliable tricks. When you can see a male and female next to each other, the differences in spacing and genital shape become much more obvious than when you’re looking at a single kitten in isolation. If you’re still unsure, waiting until the kitten is six to eight weeks old makes identification significantly easier. By that point, the testicles are usually palpable and the size difference in the gap between openings is unmistakable.
Kittens with retained testicles can fool even experienced rescuers. If only one or neither testicle has descended, the area between the openings looks flatter than expected for a male. The round genital opening and wider spacing are still present, though, so those remain your most reliable visual cues regardless of age.