How to Tell If a Cat Is Neutered
To tell if a cat is neutered, start by checking to see if the tip of its ear has been clipped, which is a common sign that the cat has been neutered. Alternatively, check its inner ear for a tattoo, but be aware that the letter “M” means that the cat has been microchipped. If your cat's ears aren't clipped or tattooed, put on latex gloves and hold the cat securely so you can check its genital region. Then, locate its testicle sac, which is below its tail and anus and above its penis, and feel around gently. If you feel 1 or 2 hard balls inside, the cat hasn't been neutered.
Position your cat. To check your cat yourself, you need to have access to his buttocks area in order to examine his genital region. You should position your cat with his rear end toward you. Once he is positioned, you need to pull his tail straight up so you can see his genital region. You may need to get someone to help you if you think your cat will squirm around while you do this. You can stroke your cat's back and talk to him to make him put up his tail on his own. This way, you won't have to hold it and he will be more relaxed. You might also want to put on a pair of latex gloves since you are going to be feeling around your cat's genitals. Make sure they are thin enough that you can still feel through them. Move the fur out of the way, if necessary. If your cat is fluffy, you may need to move excess fur out of the way to see the genital region. Move the fur out of the way to look underneath at the genital region. Once you spread the fur between his legs, you should see his penis and anus. Make sure you are careful and don't push too hard. You don't want to hurt your cat. If your cat is short haired, you may not need this step because this area will be obvious without having to move any fur around. If you cat is calm or docile, you may be able to do this with him lying on his back. If you try this, grab the scruff of his neck and turn him over. This will keep him in place and help protect your hands and arms in case he lashes out at you with his claws. Check for the testicles. When your cat gets neutered, he has his testicles removed. Because of this, you can feel this area to see if your cat has been neutered. Look for his testicle sac, which is located below the tail and anus and above the penis. There should be a small bag there. Pick it up and gently feel what's inside. If there are hard balls inside, your cat still has his testicles and he is not neutered. If the sac is soft, he most likely has been neutered recently. This is usually accompanied by a shaved scrotum as well. If there is no sac to be held, he may have been neutered more than a month ago and the sac has gone flat. If you find one testicle, your cat has not been neutered. This is not a 100% guarantee that your cat has been neutered. If you cat is young, he also may not have dropped his testicles yet. He also may suffer from cryptorchidism, a condition where neither of the testicles have dropped. Measure the length between the anus and penis. There is another way you can check to see if your cat has been neutered. Pull up his tail. Measure the spacing between his anus and his penis. If the area is more than 1 inch wide, then your cat has likely been neutered. If your cat is young, the spacing needs to be a little over 1/2 an inch. Look for it in writing. When you're buying or adopting a cat or kitten, ask if he comes with any paperwork. There may be a certificate or letter from a vet to prove that the cat has been neutered. Also don't be afraid to ask. If you are buying the cat from a pet store or adoption agency that doesn't give you any paperwork, ask them if they know if your new cat has been neutered. It is not an indelicate question and makes you more responsible as an owner. Check his ear. If there is no information available when you adopt your cat, or if you found a stray cat, you can check his inner ear for tattoos. Check for tattoos or clipped ears. These signs usually mean the cat has been neutered. There is one tattoo that doesn't mean he has been neutered. If you see a letter M, that means the cat has been micro-chipped. Look at his lower body fur. When you pick up the cat, look at the fur around his lower body. If it is shaved or if it looks shorter than the rest of his fur, he may have been neutered. Vets have to shave off the fur in that area before performing the neutering operation, so it can be an indication. This is not a foolproof method, so you should try another method in addition to this one. Notice if his urine smells particularly bad. Intact tom cats produce a particularly pungent and offensive smelling urine. If your cat produces very smelly urine, then he may be intact or just recently neutered. Ask your veterinarian. If you have tried all other methods and are still not sure, you should ask your veterinarian if the cat has been neutered. She will be able to tell you because she can look for things on your cat that you might not be aware of. Let them know when you go in what your concern is. If you find out that your cat isn't neutered, you should make an appointment to get it done as soon as possible. 
Position your cat. Move the fur out of the way, if necessary. Check for the testicles. Measure the length between the anus and penis. Look for it in writing. Check his ear. Look at his lower body fur. Notice if his urine smells particularly bad. Ask your veterinarian. 