Kitten Growth Chart: Kitten Weight by Age, Body Condition and When to Worry

A healthy kitten is born weighing about 100 grams (3.5 ounces), should double that in the first two weeks, and then keeps gaining, about 50 to 100 grams a week in the early weeks (International Cat Care; Merck Veterinary Manual). There is no single kitten growth chart that fits every cat: breed, sex and litter size all change the numbers, and a large breed can still be growing at a year old. What matters most is a steady upward line for your own kitten, weighed on the same scale, plus a body condition score that stays in the ideal range.

That is a job for a record rather than a calculator. Creatures does not have a cat or kitten weight calculator (its weight calculators cover livestock and horses), but every kitten can have a free profile where you log each weigh-in and see the trend on a chart. You can start your kitten’s profile with no account needed, and the section on charting your kitten’s weight explains how it works. This guide gives the published reference points, week-by-week checkpoints, how vets use growth charts and body condition scores, and the warning signs that mean a call to the vet.

Kitten weight by age: the published reference points

There is no official kitten growth chart from a veterinary body that covers every cat from birth. What exists is a set of well-sourced reference points for the first weeks, and a set of research growth charts for domestic shorthair kittens from 8 weeks on.

Birth. International Cat Care says kittens weigh around 100 grams at birth. In a UK study of 1,056 pedigree litters, live-born kittens averaged 93.5 grams, and kittens were lighter in larger litters and heavier after longer pregnancies (Sparkes and colleagues, 2006).

The first day. Merck’s guide to neonatal care, written by a veterinary reproduction specialist, says a mild loss of up to 10 percent of birth weight is acceptable on day 1 (Merck Veterinary Manual). After that, the line should go up every day.

The first weeks. International Cat Care expects kittens to double their birth weight in the first two weeks and then gain steadily. Merck gives a normal neonatal gain of 5 to 10 percent of body weight a day and, for kittens specifically, 50 to 100 grams a week. Merck’s owner guide adds that kittens gaining weight every day after the first 24 hours is the sign that the mother’s milk supply is adequate (Merck Veterinary Manual, owner version).

After 8 weeks. Researchers at the University of Liverpool and the Waltham Petcare Science Institute built growth standard charts for intact male and female domestic shorthair kittens from 8 to 78 weeks, using weights from client-owned kittens that stayed healthy and at ideal body condition (Salt and colleagues, 2022). The charts are centile curves, like a pediatrician’s chart for a child: rather than one “right” weight for each age, they show a range, and a healthy kitten tends to stay near its own centile line.

What the numbers mean week by week

We are not printing an invented gram-by-week table, because no veterinary source we found publishes one for kittens from birth, and an average table can make a struggling kitten look fine. What the sources do support is a set of checkpoints:

• Birth: about 100 grams (International Cat Care), with live-born kittens averaging 93.5 grams in the UK pedigree study.
• Day 1: a dip of up to 10 percent of birth weight is acceptable (Merck). After that, the weight should go up every day.
• First week: a gain of 5 to 10 percent of body weight a day is normal in newborns (Merck), so a 100 gram kitten should be putting on several grams daily.
• By 2 weeks: about double the birth weight (International Cat Care).
• The early weeks: a steady gain that Merck puts at about 50 to 100 grams a week for kittens.
• From 8 weeks: your veterinarian can plot weights on a growth centile chart, such as the domestic shorthair standards from Salt and colleagues, alongside a body condition score.

The most useful test is not whether your kitten matches someone else’s number, but whether its own line keeps rising. A kitten that loses weight after the first day, stays flat between weigh-ins, or gains clearly less than these checkpoints needs a veterinarian, especially in the first weeks.

You will see a “one pound per month” rule of thumb for kittens. We could not find a primary veterinary source for it, so we do not use it here; ask your vet what gain to expect for your kitten’s breed and age.

Milestones to note alongside the weights

Weight is one line on the chart; development is the other. International Cat Care’s guide to bringing up a litter of kittens gives these milestones:

• Eyes open any time between 2 and 16 days, most commonly around 7 to 10 days.
• Walking from around three weeks, and a low-sided litter tray from about the same age.
• Solid food from around four weeks. Weaning should begin at three to four weeks, be almost complete by seven weeks, and be finished by around six to eight weeks.
• Vaccinations from around 8 to 9 weeks. Our kitten vaccination schedule explains the core vaccines and timing to discuss with your vet.
• Neutering before sexual maturity. International Cat Care suggests around 4 months, and the American Association of Feline Practitioners supports spaying or neutering cats not intended for breeding by 5 months of age. Our guide to the cat in heat explains why that timing matters for female kittens.

Weaning is a time to watch the curve closely, because the kitten is switching food sources. A kitten that loses weight, or stays flat for more than a couple of weigh-ins, needs a veterinarian’s opinion.

How breed and litter size change the curve

Breed sets the finish line. A Selkirk Rex, for example, is a heavy-boned breed whose adult males weigh 12 to 15 pounds according to the Cat Fanciers’ Association, and whose coat keeps developing until about two years old, so a Selkirk Rex kitten can look small next to its eventual size for a long time. A small, fine-boned breed will sit on a lower curve from the start. That is why the published growth standards are specific to domestic shorthairs, and why breeders’ own records for their lines are worth asking about. Our guide to how many kittens a cat can have covers litter size, which matters here too: in the UK pedigree study, kittens from bigger litters were lighter at birth.

Sex matters as well. The Salt study built separate charts for males and females, because intact males and females grow differently through the first year and a half.

Is my kitten the right weight? Body condition scoring

A weight on its own does not tell you whether a kitten is lean or chubby, which is why veterinary guidelines pair weight with a body condition score. The 2021 AAHA/AAFP Feline Life Stage Guidelines define the kitten stage as birth to 1 year and say that body weight, body condition score and muscle condition score are important parts of the physical exam at all life stages, adding that obesity prevention starts with kittens (Quimby and colleagues, 2021).

The most widely used scale is the 9-point chart from the World Small Animal Veterinary Association (WSAVA body condition score for cats). In short:

• 1 to 3, under ideal. At 3, ribs are easily felt with minimal fat covering, the waist behind the ribs is obvious, and the lumbar vertebrae are obvious.
• 4 to 5, ideal. At 5, the cat is well proportioned, ribs can be felt with a slight fat covering, a waist is visible behind the ribs but not pronounced, and the abdominal fat pad is minimal.
• 6 to 9, over ideal. At 7, ribs are not easily felt through moderate fat, the waist is hard to see and the belly may be slightly rounded. At 9, ribs cannot be felt under heavy fat.

To check your kitten, run your flat hands gently along its sides: at the ideal score you should feel the ribs under a slight fat covering and see a waist behind the ribs. Ask your vet to score your kitten at each visit and show you what a 5 feels like on your own cat.

What the growth charts add. In the Salt study, kittens that became overweight started heavier and then crossed upward through two or more centile lines, while the few underweight kittens dipped first. The authors suggest that a kitten crossing centiles is a reason to review diet and care with the vet, not a diagnosis. Weighing on a schedule is what lets you see that drift early.

When kitten weight is a reason to call the vet

Newborn kittens can go downhill very quickly, International Cat Care warns. Call your veterinarian promptly if:

• A kitten loses weight after the first day, or does not gain for a day or two in the first weeks. Failure to gain weight is listed among the warning signs in the veterinary textbook The Cat (Little, The Cat).
• A kitten is crying constantly or failing to suckle, which International Cat Care says usually means hunger or illness.
• A kitten is weak, cold, or bringing milk back up.
• The mother has hot, swollen or painful mammary glands, neglects the kittens, or the kittens fail to thrive, which Merck lists as possible signs of mastitis (Merck Veterinary Manual).
• An older kitten drops weight, stops eating, or has diarrhea or vomiting.

Merck notes that kittens cannot regulate their own body temperature until about 4 weeks of age and that a chilled newborn must be rewarmed slowly, so keep the nest warm and draft-free and call your vet at once about a kitten that feels cold. Do not give any medicine or milk replacer changes without your vet’s advice.

Charting your kitten’s weight on Creatures

Creatures has no cat weight calculator, and a calculator would not help much anyway: a kitten’s weight comes from a scale, not a formula. What Creatures does is keep every weigh-in on the kitten’s own profile and draw the curve for you. Saving records needs a free account; the profile form opens without one.

1. Add each kitten. Create a profile for your kitten. If you bred the litter, record the birth on the mother’s profile instead: one form saves the litter and creates a profile for each kitten, linked to both parents. See recording births and creating a litter.
2. Log each weigh-in. On the kitten’s Records tab, choose Add record, then Physical Measurement, and pick Measured weight. Enter the value in grams or ounces; the form starts on the unit you used last and asks before saving if a number looks like the wrong unit. See adding a record.
3. Read the curve. Open Measurements on the Records tab to see a chart of every reading, with the latest weight, the change over the period you pick, an average daily gain and a table of exact readings. See track weight and growth.
4. Keep to a schedule. Track regularly sets up a care plan for weigh-ins, or add a repeating Reminder for each weigh day. See reminders and upcoming care.
5. Weigh the whole litter in one go. If the kittens are in a group of profiles, Physical measurement on the group’s Overview opens a batch panel with one row per kitten. See weigh or measure a whole group at once.
6. Add photos and a body condition score. A photo on a measurement record lines up under Progress photos with its date, and a body condition score can be logged as a measurement too. When the kitten goes to its new home, transferring the profile passes its records to the new owner.

For a pedigreed kitten, the free cat pedigree chart maker builds a printable family tree for the new owner, and our guide to cat pedigree papers explains CFA and TICA registration. If you are tracking a kitten’s health beyond weight, the cat health record template lists what else is worth keeping.

Kitten growth chart FAQ

How much should a kitten weigh at 8 weeks?

There is no single sourced number. Breed, sex and litter size all change it, which is why the published growth standards from 8 weeks are centile charts rather than one figure. Ask your vet to plot your kitten on a growth chart and check its body condition score; what matters is a curve that keeps rising and a score of 4 to 5 of 9.

How much weight should a newborn kitten gain each day?

Merck gives 5 to 10 percent of body weight a day for newborns, and International Cat Care expects birth weight to double within two weeks. A small dip on day 1 is acceptable; after that, the weight should rise daily.

How often should I weigh kittens?

Merck’s neonatal guide suggests daily for the first two weeks, then every three days until a month old. Its owner guide suggests weighing as soon as the kittens are dry and twice a day in the first week. After the first month, pick an interval you can keep, such as weekly, and weigh at every vet visit too.

When do kittens stop growing?

Most of the growth happens in the first year, which the AAHA/AAFP guidelines treat as the kitten stage, but the research growth charts run to 78 weeks, and heavy-boned breeds can keep filling out into their second year.

Is there a kitten weight calculator on Creatures?

No. Creatures has weight calculators for some livestock and horses but not for cats. For a kitten, log real weights on its free profile and Creatures charts the trend.

What is a healthy body condition score for a kitten?

On the WSAVA 9-point scale, 4 to 5 is ideal: ribs felt under a slight fat cover and a visible waist. Ask your vet to score your kitten at each visit.

Do this next on Creatures

Whether you are weighing a whole litter twice a day or checking one new kitten each week, these are the useful next steps. More cat guides and breeds are on the Creatures cat page.