Cat Care

Kitten Weight Chart by Age: What's Normal from Birth to 12 Months?

By PetPawCalc Team · July 17, 2026 · 9 min read · How we write

“My kitten weighs 3 pounds — is that normal?” The honest answer is: it depends entirely on age, and a little on breed. A 3 lb kitten at 8 weeks is unusually large; a 3 lb kitten at 4 months is right on schedule; a 3 lb Maine Coon at 6 months is small for their breed but might still be perfectly healthy.

Here’s a birth-to-12-month weight chart, the fastest rule of thumb for checking growth, and how to tell if something’s actually off track versus just normal breed variation.

Kitten Weight Chart: Birth to 12 Months

This kitten growth chart applies to typical domestic shorthair/mixed-breed kittens — the majority of kittens. Large breeds are covered separately below, since their growth timeline is meaningfully different.

Age Expected Weight Range
Birth 3–4.5 oz (85–130g)
1 week 4–6 oz (110–170g)
2 weeks 7–9 oz (200–255g)
4 weeks (1 month) 1–1.5 lbs (450–680g)
8 weeks (2 months) 1.5–2.5 lbs (680g–1.1kg)
3 months 2.5–3.5 lbs (1.1–1.6kg)
4 months 3.5–4.5 lbs (1.6–2kg)
5 months 4.5–5.5 lbs (2–2.5kg)
6 months 5–6.5 lbs (2.3–3kg)
7 months 5.5–7 lbs (2.5–3.2kg)
8 months 6–7.5 lbs (2.7–3.4kg)
9 months 6.5–8.5 lbs (3–3.9kg)
12 months 7–10 lbs (3.2–4.5kg), near adult weight

Kitten Age and Weight Chart, Week by Week

The months above are what most people need. If your kitten is under about four months, weeks are the more useful unit — they change fast enough that a month-wide band is close to useless. This is the same curve, read weekly.

Age Expected Weight
1 week 4–6 oz (110–170g)
2 weeks 7–9 oz (200–255g)
3 weeks 12–16 oz (350–450g)
4 weeks 1–1.5 lbs (450–680g)
6 weeks 1.2–2 lbs (550–900g)
8 weeks 1.5–2.5 lbs (680g–1.1kg)
10 weeks 2–3 lbs (900g–1.4kg)
11 weeks 2.2–3.2 lbs (1–1.45kg)
12 weeks 2.5–3.5 lbs (1.1–1.6kg)
14 weeks 3–4 lbs (1.4–1.8kg)
15 weeks 3.2–4.2 lbs (1.45–1.9kg)
16 weeks 3.5–4.5 lbs (1.6–2kg)

A rough sanity check that works well up to about four months: a kitten gains roughly 100g, or a quarter of a pound, every week. If your kitten is putting on close to that, the exact row matters less than the trend.

Newborn kittens grow fastest of all: a healthy nursing kitten typically gains 10–15 grams per day in the first few weeks. A kitten who isn’t gaining daily in that window should be checked by a vet — at that size, there’s very little margin for error.

If you prefer a kitten weight chart in grams and kilograms rather than pounds, the metric figures above are the same numbers converted — the chart works as a kitten weight chart kg either way, and grams are the more practical unit under about 8 weeks, when a few ounces either side is a meaningful difference.

How Much Should My Kitten Weigh at Each Age?

The table above is the quick reference. Below is the same curve read age by age, with the thing worth knowing at each stage — because the answer changes fast in the first few weeks and slows down considerably after five months. In one sentence: about 100g at birth, then roughly a pound a month until five months, reaching 7–10 lbs by the first birthday.

How much does a newborn kitten weigh? 3–4.5 oz (85–130g) — roughly the weight of a deck of cards, and about four inches long. Kittens under about 3 oz at birth, or from very large litters, are worth watching closely. By the end of the first week expect them to have roughly doubled.

How much weight should kittens gain per week? About 100g per week, or a little under ¼ lb, through the first several weeks — which is the weekly version of the 10–15g per day figure above. A kitten who stalls for more than 2–3 days, or loses weight at all, needs a vet, not another day of watching.

How much should a 3 week old kitten weigh? Around 350–450g (12–16 oz). This is the week the first baby teeth push through and kittens start to walk properly rather than wobble.

How much should an 8 week old kitten weigh? 1.5–2.5 lbs (680g–1.1kg). Eight weeks is the typical earliest rehoming age, so this is the figure most new owners check first — a kitten noticeably under it is worth raising at the first vet visit.

How much should a 10 week old kitten weigh? Roughly 2–3 lbs (900g–1.4kg). Under about 1.5 lbs at this age is worth mentioning to your vet — intestinal parasites are very common now and are one of the most frequent reasons growth flattens out.

How much should a 12 week old kitten weigh? 2.5–3.5 lbs (1.1–1.6kg) — the same as the 3-month row, since the two land in the same place. A kitten at around 3 lbs here is exactly on the “1 pound per month” line.

How much should a 4 month old kitten weigh? About 3.5–4.5 lbs (1.6–2kg) — 16 weeks, the same row. At this stage a kitten is roughly half-grown in length but nowhere near half-grown in bulk; the filling-out comes later.

How much should a 5 month old kitten weigh? Around 4.5–5.5 lbs (2–2.5kg). This is where the 1-pound-per-month rule starts to break down, and growth becomes less predictable from age alone.

How much should a 6 month old kitten weigh? About 5–6.5 lbs (2.3–3kg). A figure that seems low here is often a large-breed kitten on a slower timeline rather than a problem — check the large-breed table below before worrying.

How much should a 7 month old kitten weigh? Roughly 5.5–7 lbs (2.5–3.2kg), which is usually already 70–80% of adult weight for a typical domestic shorthair.

How much should an 8 month old cat weigh? Around 6–7.5 lbs (2.7–3.4kg). Sitting a little under this is common in smaller-framed females and is not usually a concern on its own.

How much should a 9 month old kitten weigh? About 6.5–8.5 lbs (3–3.9kg), matching the 9-month row above. Growth has slowed a great deal by now; most of what remains is filling out rather than getting longer.

How much should a one year old cat weigh? Typically 7–10 lbs (3.2–4.5kg) for a domestic shorthair, which is essentially adult weight. Large breeds are the exception and keep growing — a Maine Coon at twelve months is nowhere near finished.

A Few Things the Chart Doesn’t Show

Growth isn’t quite linear, so in-between ages interpolate. A kitten at 3.5 months sits between the 3- and 4-month rows at roughly 3–4 lbs; at 4.5 months, around 4–5 lbs. Through this stage splitting the difference is close enough.

“How big” and “how much should they weigh” are the same question. Size in a growing kitten is tracked by weight, not by length — frame and body length vary so much between individuals that a measuring tape tells you very little. This is also why there is no useful way to judge a cat’s weight from its length: body condition assessed by feel is what veterinary practice uses instead, and the chart above is only the starting point for that.

Past about four months, “kitten” and “cat” get used interchangeably. The figures do not change when the word does. A cat at twelve months is at roughly adult weight for a domestic shorthair — 7–10 lbs — while large breeds are still growing.

Averages hide normal variation. Healthy kittens of the same age routinely differ by a pound either side, so treat each range as a band rather than a target. A kitten tracking steadily along the low edge of the band is usually fine; one that has stopped moving up it is the one to ask about.

Working Backwards: Estimating Age From Weight

If you’ve found a kitten and don’t know their birthday, the same chart runs in reverse. The rough rule for age of kittens by weight is 1 pound ≈ 1 month old, reliable up to about 5 months: a 1 lb kitten is around 4 weeks, a 2 lb kitten around 8 weeks, a 3 lb kitten around 12 weeks. So a 3lb kitten age estimate is roughly three months, and a kitten weighing 3.5–4 lbs is likely around 3.5 to 4 months.

Weight alone is the least reliable of the aging methods, though, because a kitten who has been underfed or has a heavy parasite load will weigh well below their true age. Eyes (closed until roughly 7–14 days), teeth (baby teeth from about 3 weeks, adult teeth from 3–4 months), and mobility are all better indicators, and a vet can narrow it down properly in one visit. Use weight as a cross-check, not the answer.

The Fast Rule: 1 Pound Per Month

If you don’t want to look up a chart, the shortcut vets commonly use is: a kitten gains about 1 pound (450g) for every month of age, up through roughly month 4 or 5.

This rule is convenient but has real limits. It’s built around an average domestic cat reaching roughly 8–10 lbs as an adult, so it naturally stops being useful once growth slows after month 5 — and it never applied well to large breeds in the first place (see below). Use it as a quick sanity check, not a target.

Wondering How Big Will My Cat Get?

Enter your kitten's current age and weight to get a predicted adult size range and a body-condition read.

Use the Cat Size Calculator →

Large Breeds Grow on a Different Timeline

This is the single biggest reason kitten weight charts confuse people: most charts (including the one above) describe a typical domestic shorthair or mixed-breed cat. Large breeds don’t follow it.

Breed type Reaches adult weight 6-month weight vs. chart Adult weight
Domestic shorthair / mixed 10–12 months On track with chart above 8–10 lbs (3.6–4.5 kg)
Siamese, Oriental breeds 10–12 months Often slightly under chart (naturally leaner build) 6–10 lbs (2.7–4.5 kg)
Maine Coon 3–5 years Normally below the chart at 6 months 12–20 lbs (5.4–9 kg); males up to 25 lbs (11 kg)
Ragdoll 3–4 years Normally below the chart at 6 months 10–20 lbs (4.5–9 kg)
Norwegian Forest Cat, Siberian ~3 years Normally below the chart at 6 months 10–16 lbs (4.5–7.3 kg)

If you have a Maine Coon or Ragdoll kitten who looks “small for their age” next to a generic chart at 6 months, that’s usually expected — these breeds pack on the bulk of their size in years two and three, not in the first year. Comparing them to a domestic-shorthair chart and concluding something is wrong is one of the most common mistakes new large-breed-kitten owners make.

Why Isn’t My Kitten Gaining Weight? A Quick Troubleshooting Guide

Not every plateau or slow week means trouble, but a few patterns are worth knowing:

Normal, don’t worry:

Worth a vet call:

Intestinal parasites are the single most common reason an otherwise well-fed kitten fails to gain weight — a fecal test at your first kitten vet visit rules this out quickly and cheaply, and is worth doing even without symptoms.

Body Condition: The Check That Matters More Than the Number

Once a kitten is a few months old, the same rib-and-waist check used for adult cats works well:

A kitten who passes this check is very likely at a healthy weight for their frame, even if their number sits outside the generic chart — especially for large or naturally lean breeds.

Not Sure How Your Kitten Compares by Age?

Our Cat Age Calculator converts your kitten's age into human-year equivalents so you know exactly what growth stage they're in.

Check age stage →

When to Stop Tracking Growth Weekly

Once a kitten passes about 6 months, growth slows enough that weekly weigh-ins usually aren’t necessary — monthly is plenty until they reach adult size (10–12 months for most cats, 2–4 years for large breeds). After that, treat weight monitoring the way you would for an adult cat: a check every few months is enough unless your vet advises otherwise.

Frequently Asked Questions

How much should a kitten weigh at 8 weeks? Most kittens weigh 1.5–2.5 lbs (680g–1.1kg) at 8 weeks, regardless of breed — breed-size differences aren’t very visible yet at this age. This is also the typical age kittens are weaned and rehomed, so it’s the number most new owners compare against first.

Is there a quick rule for kitten weight by age? Yes — the widely used rule of thumb is that a healthy kitten gains roughly 1 pound (450g) per month for the first 4–5 months. So a 3-month-old kitten should weigh around 3 lbs, a 4-month-old around 4 lbs. It’s an estimate, not a guarantee, and it breaks down after about 5 months as growth slows — but it’s a fast first check.

How is a kitten’s growth different from a large-breed kitten like a Maine Coon? Domestic shorthair and most mixed-breed kittens reach close to their adult weight by 10–12 months. Large breeds — Maine Coon, Ragdoll, Norwegian Forest Cat, Siberian — grow far more slowly and don’t finish filling out until 2–4 years old, so comparing their 6-month weight to a generic chart will make them look small when they’re actually right on track for their breed.

What if my kitten isn’t gaining weight? A kitten who goes more than 2–3 days without weight gain in the first 8 weeks, or who loses weight at any age, needs a vet visit — kittens have very little reserve and can decline quickly. Common causes include intestinal parasites (extremely common in kittens), inadequate calorie intake, dental issues once they start eating solid food, and underlying illness.

Can a kitten be overweight? Yes, though it’s less common than in adult cats. It usually happens with free-fed kittens on high-calorie kitten food who become sedentary indoor-only cats. Because kitten food is calorie-dense by design (to fuel rapid growth), it’s worth switching to measured meals and monitoring body condition once a kitten is neutered or spayed, since metabolism typically slows afterward.

When should I switch my kitten to adult cat food? Most kittens can transition to adult food around 10–12 months, once growth has mostly leveled off. Large breeds that are still actively growing at 12 months (Maine Coon, Ragdoll, and similar) often stay on kitten or all-life-stages food a few months longer — ask your vet if you’re unsure whether your kitten’s breed is still in an active growth phase.

Is there a Maine Coon weight predictor? There’s no precise formula for predicting an individual Maine Coon’s adult weight, since genetics and litter size vary widely, but the large-breed comparison table above works as a rough weight predictor: Maine Coons stay well below a standard kitten chart through their first year, then keep growing for another 2–3 years to reach their typical adult range of 12–20 lbs (up to 25 lbs for some males).

How big will my cat get? For a typical domestic shorthair or mixed-breed kitten, the birth-to-12-month chart above gets you most of the way there — most land around 7–10 lbs as adults. If growth is still climbing well past 12 months instead of leveling off, check the large-breed comparison table above first, since Maine Coons, Ragdolls, Norwegian Forest Cats, and Siberians keep growing for 2–4 years and land much larger (12–20+ lbs).

Is there a kitten weight calculator or kitten size calculator? Rather than a kitten weight calculator, this page uses a chart plus a simple rule you can do in your head: a kitten gains about 1 pound per month for the first 4–5 months, so age in months roughly equals weight in pounds. For adult size, our Cat Weight Calculator has a kitten adult weight mode that estimates where a growing kitten will land, which is the closest thing to a kitten size calculator — but for large breeds like Maine Coons, the breed table matters more than any formula.

How much should my kitten weigh? How much should my kitten weigh depends almost entirely on age. As a fast check: about 100g at birth, 1 lb at 1 month, 2 lbs at 2 months, 3 lbs at 3 months, and 4 lbs at 4 months, after which growth slows and becomes less predictable. The full birth-to-12-month chart above gives the ranges, and body condition — whether you can feel ribs easily but not see them — matters more than hitting an exact number.

Always consult your veterinarian with concerns about your kitten’s growth or nutrition. Individual genetics play a large role, and these charts are averages — not guarantees for any specific cat.