Kitten Weight Chart by Week and Month (Grams, kg and lb)

A healthy kitten is born at roughly 90–110 g, doubles that weight within its first one to two weeks, and gains about 10–15 g a day early on. By 8 weeks most kittens weigh 750–1000 g, by 4 months around 1.7–2.0 kg, and by 12 months a typical domestic cat sits at 3.2–4.5 kg. Steady gain matters more than any single number, so use the charts below as a guide and weigh often.

The short answer

• Birth: 90–110 g (3–4 oz). Kittens under about 75 g at birth need extra watching.
• Weeks 1–2: birth weight should roughly double before day 14. Expect 10–15 g of gain per day.
• Weeks 2–16: about 50–100 g per week early on, rising to around 100 g or more per week from roughly 2 months.
• Rule of thumb: a kitten's weight in pounds is roughly its age in months up to about 5–6 months.
• Red flag: any weight loss over 24 hours in a newborn, or no gain for two days in a kitten under 8 weeks, is a reason to call a vet the same day.

Kitten weight chart by week (0–16 weeks)

These ranges are for an average domestic shorthair kitten. They line up with veterinary references (birth weight of 90–110 g, birth weight doubled before 2 weeks, 50–100 g gained per week in the first months) and with rescue-group age guides. Large breeds and big litters can sit at the top or bottom of a range and still be perfectly healthy.

A few things to keep in mind when reading the week-by-week chart:

• In the first 24 hours a newborn can lose up to about 10% of its birth weight. After that, the number should climb every day.
• The trend is what counts. A kitten that starts at 85 g and gains 12 g every day is doing better than one that starts at 110 g and stalls.
• Littermates rarely weigh the same. A kitten that keeps falling further behind its siblings deserves a closer look, even if it is still inside the range.

Kitten weight chart by month (1–12 months)

After the first few months, weekly changes get smaller relative to body size, so a monthly view is easier to follow. The figures match our cat weight chart by breed, which continues into adult weights.

Growth is fastest in the first four to five months. From about 6 months it slows down and the range widens, because breed, sex and neutering start to show. A 9-month-old kitten at 3.0 kg and one at 3.9 kg can both be healthy; body condition (you can feel the ribs under a thin layer of fat, and there is a visible waist from above) tells you more than the scale alone at this age.

How to weigh a kitten

You do not need special equipment. A digital kitchen scale that reads in single grams is accurate enough for kittens up to about 2–3 kg.

1. Put a small bowl or box on the scale and press tare so it reads zero.
2. Place the kitten in the bowl and wait for the reading to settle. A wriggly kitten can be weighed in a closed carrier on a larger scale instead.
3. Write the number down straight away with the date and time.
4. For older kittens, you can weigh yourself holding the kitten on a bathroom scale and subtract your own weight, but this is only accurate to about 100–200 g.

How often to weigh depends on age:

• Newborns to 4 weeks: once a day, at the same time, ideally just before a feed. Bottle-fed orphans are often weighed twice a day.
• 4–8 weeks: daily or every other day, especially around weaning.
• 8 weeks to 6 months: once a week.
• 6–12 months: every two to four weeks.

Log every weigh-in in PetVitals. The weight chart shows the growth curve and reminds you of vaccines and deworming.

Kitten not gaining weight: causes and when it is an emergency

A kitten that stops gaining, gains slowly, or loses weight is telling you something is wrong. The common causes are:

• Not enough milk or food. The mother may have too little milk, a large litter may push the smallest kitten off the teats, or a bottle-fed kitten may be getting a too-weak formula or too few feeds. During weaning, some kittens simply do not eat enough solid food yet.
• Intestinal parasites. Roundworms, hookworms, coccidia and giardia are very common in young kittens and steal nutrients, cause diarrhea and a pot belly. Routine treatment usually starts at 2–3 weeks; see how often to deworm a cat for the schedule. Fleas can also cause anemia in tiny kittens.
• Infections and illness. Upper respiratory infections block the nose so kittens cannot smell or suckle well. Diarrhea, panleukopenia and other infections cause rapid weight loss. Vaccines from around 6–8 weeks protect against the worst of these; the cat vaccination schedule by age has the timing.
• Being too cold. Newborns cannot regulate their body temperature. A chilled kitten stops digesting and stops nursing.
• Congenital problems. Cleft palate, heart defects and other birth defects can make feeding or growing difficult.
• Fading kitten syndrome. This is a term for kittens that seem normal at birth and then decline, usually in the first weeks. Low birth weight, poor nursing, infection, low blood sugar and hypothermia all play a part. A fading kitten can go downhill within hours.

When to call a vet straight away

Kittens under 8 weeks have almost no reserves, so weight changes are urgent at this age:

• A newborn (under 2 weeks) that loses any weight over 24 hours, after the normal first-day dip.
• A kitten under 8 weeks with no weight gain for two days in a row.
• Weight loss together with crying, weakness, not suckling, a cold body, diarrhea or labored breathing.
• A kitten that is falling clearly behind its littermates week after week.

Keep a weak kitten warm while you arrange the visit, but do not force-feed a cold kitten, as it cannot digest properly. For older kittens, a stall of a week or more, poor appetite, vomiting or lethargy also needs a vet; our list of signs your cat is sick covers what else to look for.

Male vs female kittens and breed differences

In the first couple of months, males and females grow at much the same rate. From around 4–5 months males usually pull ahead, and by adulthood a male domestic cat is often 0.5–1.5 kg heavier than a female from the same litter. If you have a mixed litter, compare each kitten with its own curve rather than with its siblings of the other sex.

Breed makes a bigger difference than sex:

• Large breeds such as the Maine Coon, Norwegian Forest Cat, Ragdoll and Siberian are born heavier and keep growing for much longer. A Maine Coon kitten can be 2–3 kg at 4–5 months and may not reach full adult size until 3–5 years old.
• Small and slender breeds such as the Siamese, Oriental, Devon Rex and Singapura often have smaller kittens and finish near the bottom of the ranges above.
• Mixed-breed kittens usually follow the average chart closely.

For adult targets by breed, see the cat weight chart by breed.

When does a kitten reach adult weight?

Most domestic cats reach about 80–90% of their adult weight by 9–12 months and are fully grown somewhere between 12 and 18 months. After the first birthday, many cats still add a few hundred grams of muscle and frame over the next several months. Large breeds are the exception: Maine Coons, Ragdolls and Norwegian Forest Cats keep filling out until 2–5 years of age.

Neutering, usually done around 4–6 months, lowers energy needs. Kittens that keep eating the same amount after surgery often start gaining too fast, so this is a good moment to check the curve and adjust portions.

Feeding notes for steady growth

• 0–4 weeks: mother's milk, or kitten milk replacer every 2–3 hours for orphans. Never give cow's milk.
• 4–8 weeks: weaning. Offer wet kitten food mixed with milk replacer as a gruel, then gradually thicken it.
• 8 weeks to 6 months: a complete kitten food, split into about four to five small meals a day. Kittens need roughly two to three times the calories per kilogram of an adult cat.
• 6–12 months: move to two or three meals a day. Most cats switch to adult food around 12 months; large breeds may stay on kitten food longer.

Aim for slow, steady growth rather than the fastest possible gain. Overfeeding a kitten does not make a bigger cat, only a fatter one. Use the feeding guide on the food label as a starting point, then adjust based on weight and body condition; how much to feed a dog or cat explains how to work out daily portions.

The simplest habit that catches problems early is weighing on a schedule and looking at the trend. A kitten that tracks along its own curve, week after week, is almost always a kitten that is doing well.