When to Switch From Kitten to Cat Food: 5 Signs it’s Time
Deciding when to switch from kitten to cat food can feel like a momentous (and often overwhelming) call for many pet parents. As a veterinarian, questions about this topic are among the most common ones I hear from cat moms and dads. And that’s a good thing, because making the right choice—at the right time—is crucial for your cat’s long-term health.
Feeding your kitten an age-appropriate diet is important because kittens have significantly different nutritional requirements from adult cats. However, according to a 2021 survey of cat parents, many were a bit fuzzy on when their furry family member should transition to adult food.
If you’ve got similar questions about your kitten’s diet, we’ve got answers. Here’s a simple, science-based guide to help determine how long to feed kitten food, when to switch, and how to transition to adult cat food without a hitch.
Is Your Kitten Ready for Adult Cat Food?
To answer this question, first we must answer a different one: Why do growing kitties need kitten-specific food in the first place?
During the first year or so of their life, a kitten’s body is a bustling hive of metabolic activity. Their bones grow longer, their muscles triple in size, and both the immune and nervous systems develop rapidly. Meanwhile, their brains are busy building up stores DHA, an omega-3 fatty acid essential for brain development, as well as eye and heart health.
To fuel all this incredible growth, kittens require about two to three times more energy per pound than adult cats. They also require more protein, fat, calcium, and phosphorus per calorie than fully-grown felines.
Difference Between Kitten and Adult Cat Food
Because kittens and cats need very different things from their diet, it’s best to stick with a commercial diet that supports the nutritional needs specific to your cat’s stage of life.
Luckily, the Association of American Feed Control Officials (AAFCO) make that easy to determine. AAFCO is an independent non-profit that sets labeling and ingredient standards for U.S. animal feed and pet food.
Any diet that’s appropriate to support a growing kitten will be clearly labeled as “complete and balanced” for kittens or all life stages.
Here’s a quick overview of the differences between kitten and adult cat food.
| Nutrients AAFCO minimum, dry matter | Kitten Food labeled for “Growth & Reproduction” | Cat Food labeled for “Adult Maintenance” | Why Kitten Food Matters |
| Protein | 30% approximately 75g/1000kcal | 26%approximately 65g/1000kcal | Extra protein helps build muscle, organs, antibodies. |
| Fat | 9% | 9% | Crude fat minimums are the same, but kitten food must contain specific fatty acids that support brain and eye development, strong immune system, and healthy skin/coat. |
| Calcium and Phosphorus | 1% and 0.8 % | 0.6% and 0.5% | Increased levels for healthy frame development and tooth mineralization. |
| Feeding frequency | 3 to 4 meals/day (or free-choice feeding in tiny portions) | 2 meals/day | Small, more frequent meals keep blood glucose steady and won’t overfill tiny kitten stomachs. |
| Kibble size and texture | Smaller size, softer bite | Standard size | Smaller, softer kibble is gentler on emerging teeth |
| Caloric density | 450 to 500 kcal/cup (dry) | 350–400 kcal/cup | Calorie-dense kitten food provides more energy in fewer bites |
What if kittens eat adult food too soon? Switching to adult food too early can stunt lean-body growth, weaken bone mineralization, and leave lifelong gaps in immunity.
To avoid these negative effects, feed your kitten a diet specifically formulated for growth or all life stages until they’re fully matured.
When Is a Cat No Longer a Kitten?
Now that we know why it’s important to feed your kitty an age-appropriate diet, the next big question is when to make the switch.
Unfortunately, it’s not like your pet magically (and obviously) transforms from a kitten into an adult overnight. The answer to “How long is a cat a kitten?” can be hard to determine. The process is gradual and often depends on the individual cat.
The Feline Veterinary Medical Association recommends keeping kittens on a complete and balanced growth diet until they are fully grown and have their adult teeth. That usually happens at around 12-18 months of age for most cats.
However, that timeline that dictates when are cats fully grown can vary by breed, sex, and genetics. Here are some specific examples:
- Small-breed cats, such as Singapura and Cornish Rex, typically mature by 9–10 months of age.
- Average breeds, like domestic shorthairs and Siamese, reach maturity at around 12–14 months.
- Large breeds, such Maine Coons and Norwegian Forest Cats, may continue to fill out until age 2–4, sometimes up to 5 years.
- Mixed-breed cats usually mature at around 12 months, unless their lineage includes a giant breed.
Because growth curves vary, it’s best to watch for the practical signs below instead of relying only on the calendar.
When to Switch to Adult Cat Food: 5 Signs It’s Time
Whether you have a Burmese, Maine Coon, or a breed in between, there are several signs we can use as guidelines for when it’s time for adult food. Here are some clues to watch out for that can help you figure out when to switch from kitten food to adult food.
- Growth plateau – During kittenhood, most visits to the vet include a review of your pet’s progress on a veterinary growth chart. If the chart shows that your kitten’s weight and length haven’t changed for 6 to 8 weeks, it’s usually a sign that they’ve stopped growing and can switch to adult cat food.
- Food left in the bowl – If your kitten suddenly stops polishing off meals, that may be a sign that their body doesn’t need as many calories. It could be time to switch to a less calorie-dense adult food to satisfy their energy needs.
- Adult molars are in – Most kittens have all of their adult teeth “in wear” (meaning fully erupted or emerged) by around 11 to 12 months. These larger choppers can safely handle adult-sized kibble, which is often too large for dainty kitten teeth.
- Body condition score stabilizes – Your pet’s body condition score (BCS) is how veterinarians assess how a cat’s weight fits on their frame. Using visual cues, your vet can score your cat on a scale from 1 to 9.
- A BCS of 5 is considered normal weight
- A score of less than 5 is considered thin
- A score greater than 5 is regarded as a level of obesity.
If your kitten maintains a BCS of 4–5 for two consecutive vet visits and shows other signs of maturity, your vet may recommend starting on adult food.
- Your veterinarian’s thumbs-up – Ultimately, consult your veterinarian with any questions about whether your pet is ready for adult cat food. They can factor in all of the growth metrics, as well as any health details unique to your cat, to provide the best dietary guidance.
How to Switch from Kitten Food to Adult Cat Food
When it’s time to switch to adult cat food, here’s a simple checklist to ensure a smooth transition.
First, verify that the adult food you select says on the label that it meets the AAFCO guidelines for “adult maintenance” and has a caloric density of ≤ 400 kcal/kg.
Second, choose a diet that features the same protein your cat is accustomed to eating, if you can. For example, if you raised your kitten on a chicken-based formula, choose a similar chicken-based diet for your adult cat. A familiar diet helps reduce the risk of gastrointestinal upset.
Sometimes, that might not be possible. For example, cats with food allergies may need an alternative protein source. In these cases, always consult with your veterinarian for guidance. They can help steer you to an appropriate formula and transition plan.
Finally, if you have a large-breed kitten, choose a formula labeled “large-breed adult” to help support joint health.
Switching from kitten to cat food: Tips for success
Don’t switch too quickly. Be patient during the transition from kitten to adult food. Veterinarians generally recommend a 7-day plan:
- For the first two days, fill your pet’s bowl with 75 percent kitten food and 25 percent new adult food.
- On days 3 and 4, make the mix 50 percent of each formula.
- On days 5 and 6, shift to 25 percent kitten food and 75 percent adult food.
- By day 7, your cat should be eating adult food exclusively.
Stick with the same brand. If your kitten thrived on Brand X kitten food, consider trying that brand’s adult cat food first for an easier transition. You also may want to pick the formula that’s most like what your cat is used to eating. But feel free to switch proteins after the transition period to add variety to their nutrients.
Adjust portion sizes. After transitioning to adult cat food, it’s important to calculate how many calories your adult cat needs to thrive. You’ll need to base this calculation on your cat’s ideal weight. Generally, a 10-pound adult cat requires about 250 kcal daily, which is usually half of what you fed during kittenhood.
Sudden weight gain usually means the portion is still too large. Try reducing your cat’s overall calories by 10 percent and re-weigh in two weeks. If nothing has changed, contact your veterinarian for an appointment. They may be able to suggest a different formula or weight management cat food that better fits your cats health needs.
Watch for negative side effects. Any time you switch from one food to another, it’s important to keep an eye out for changes in your cat’s health.
Some changes are not cause for concern. For example, soft stools for 24 to 48 hours are common in cats switching from kitten to adult food.
However, if your cat experiences vomiting, diarrhea, or refuses to eat, keep a close watch. If any of these symptoms lasts more than 48 hours, it’s time to call your veterinarian.
Kitten Food vs Adult Food FAQs
Here’s a quick recap of answers to questions pet parents commonly ask about when to switch kitten to adult food.
When do kittens stop growing?
Most kittens finish rapid growth by 12–18 months, but large breed kittens can continue growing until they are 2 years old or older.
When is a cat considered an adult?
FelineVMA/AAHA (American Animal Hospital Association) have life-stage guidelines which place “young adult” status at 1 year, but full physiologic maturity varies by breed.
When can kittens eat dry food?
Healthy kittens can nibble moistened dry kibble at 5–6 weeks, but a dry-only diet isn’t recommended until weaning is complete (~8 weeks).
Can kittens eat adult cat food?
Occasionally, yes. But feeding an adult formula long-term before maturity risks nutrient deficits in protein, calcium and DHA.
Can adult cats eat kitten food?
It’s safe but calorie-dense; over time it can lead to obesity. We usually reserve kitten diets for pregnant, nursing or under-weight adults under strict veterinarian recommendation and supervision.
Kittenhood goes so quickly, before you know it, your sweet little kitty will be celebrating their first birthday. However, remember that feline adulthood isn’t measured on a calendar. When it comes to switching to adult cat food, let your pet’s growth chart, BCS and veterinarian guide your decisions.
A gradual transition ensures your kitten glides into adulthood with the nutritional support they need. No growing pains required!
