Kitten sex: how to tell a male from a female

The question comes up in the first hours: is this kitten a male or a female? On a newborn, nothing shows at a glance. No visible penis, no obvious testicles. The answer is not in what sticks out, but in the gap between two openings.

🔎 The rule, in two punctuation marks

Lift the tail gently. You will see two openings: the anus on top, the genital opening just below. Everything rests on their spacing and on the shape of the second one.

• Female — the two openings sit close together, five to eight millimetres at birth. The vulva is a vertical slit almost tucked under the anus. Together they draw a lower-case i.

• Male — the two openings are clearly apart, twelve to fifteen millimetres, because the room for the scrotum is already reserved between them. The preputial opening is round. Together they draw a colon, the « : » sign.

👉 Remember « i » for female, « : » for male. That is the only thing to memorise, and it holds from day one to weaning.

🐾 How to look without stressing the kitten

A kitten a few days old cannot regulate its temperature and tolerates separation from its mother badly. Keep it short.

• Warm your hands before picking it up.

• Lay it belly-down on a towel and lift the tail with a fingertip. Never pull it upwards.

• Look for ten seconds, no more, then give it back to its mother.

• Use the daily weigh-in: the kitten is out of the nest anyway, so the chance is free.

If the queen gets restless, stop. A litter disturbed too often is a litter the mother moves, and sometimes abandons.

📅 What you can see at each age

• At birth — the difference in spacing is already there, but it is measured in millimetres. The safest route is to compare the kittens of the litter with each other: with six side by side, the males stand out.

• Three to four weeks — the gap widens and the round shape of the prepuce becomes clear.

• Six to eight weeks — the testicles can be felt, two small soft beads between the anus and the prepuce. At that point there is no doubt left.

• Three months — the scrotum is visible without touching.

In cats the testicles descend before birth. If you cannot feel them at eight weeks, mention it to the vet: cryptorchidism can be corrected, but it is picked up early.

🎨 Coat colour: a probability, not an answer

The orange gene sits on the X chromosome. That gives two solid rules, and no certainty at all.

• Tortoiseshell, tricolour, calico — it takes two X chromosomes to show orange and black at once. These coats are almost always female. The rare tortoiseshell males are XXY and sterile.

• Solid ginger or ginger tabby — roughly three males to one female. A strong tendency, not proof.

In short: the coat steers the bet, the anatomy settles it. Never declare a sex on colour alone.

⚠️ The four classic mistakes

• Looking for a penis. It is not visible on a kitten. All you see is a small round opening.

• Judging one kitten on its own. Spacing is a relative measure: comparing siblings beats any rule in millimetres.

• Mistaking fur for anatomy. On a long-haired kitten, part the fur gently before concluding.

• Trusting a single look. Check again at around three weeks, and once more at rehoming.

📋 Why it pays to know early

This is not idle curiosity: several formalities depend on it, and a mistake is paid for in paperwork.

• Identification. The sex appears on the identification record, required before any transfer. Correcting it afterwards means filing with the registry.

• Pedigree. The litter declaration to the cat registry carries the sex of every kitten.

• Rehoming. Adopters ask the sex in their first sentence, often before the colour.

• Neutering. The timing and the cost are not the same for a male and for a female.

• The name. In France the year of birth sets the initial letter: see our guide to cat names by year.

🩺 When to ask the vet

If doubt remains after six weeks, or if you feel nothing, let the first vaccination visit settle it. It costs no time: the vet checks the sex in passing, and that is the identification appointment anyway.

For the rest of the litter, two guides go with this one: the kit for a queen giving birth and whelping in dogs and cats. And if the litter is canine the method differs: the answer is on the belly, see puppy sex.