Puppy Weight Calculator: How Big Will My Puppy Get? (Growth Chart)

Most puppies reach their adult weight somewhere between 9 and 24 months, and the bigger the breed, the longer it takes. You can get a reasonable estimate of your puppy's adult size by dividing today's weight by the share of adult weight a puppy of that size usually has at that age. It is an estimate, not a promise, but it is far better than guessing from paw size.

The short answer

• Formula: estimated adult weight = current weight ÷ typical fraction of adult weight at this age. A 16-week-old medium puppy is usually about 50% of adult weight, so 9 kg now suggests roughly 18 kg as an adult.
• Expect a range. Healthy puppies vary, so treat the result as plus or minus about 15%.
• When growth finishes: toy breeds around 9–12 months, small 10–12 months, medium 12–15 months, large 15–18 months, giant 18–24 months.
• Rules of thumb are rough. "Double the weight at 16 weeks" works fairly well for medium dogs, overestimates toy and small breeds, and underestimates large and giant ones.
• Body shape matters more than the number. A puppy who is lean with a visible waist is growing well, even if they land at the low end of the estimate.

Puppy growth chart by size

Puppies of every size grow fast at first and then slow down, but small breeds front-load their growth. In growth data from the WALTHAM Petcare Science Institute, Papillons reached half their adult weight at about 11 weeks, while English Mastiffs took about 23 weeks. The table below is the simplified chart our calculator uses. Each number is the typical share of adult weight a puppy has at that age, rounded from published growth curves.

Size classes are based on expected adult weight: toy up to about 5 kg (11 lb), small 5–10 kg (11–22 lb), medium 10–25 kg (22–55 lb), large 25–45 kg (55–100 lb) and giant over 45 kg (100 lb).

Puppy weight chart by age (example in kg)

To make the percentages concrete, here is what a typical puppy might weigh at each age, for one example adult weight in each class. Your puppy can sit above or below these lines and still be perfectly healthy; what matters is that they follow a steady curve.

Veterinary growth charts, such as the WALTHAM charts used in many clinics, work the same way: a healthy puppy tends to stay near the same curve week after week. A puppy who suddenly drops below their curve, or shoots far above it, is the one worth a closer look.

When do puppies stop growing?

Height usually finishes first. After that, many dogs keep filling out with muscle and chest depth for a few more months, which is why a large dog can look "done" at a year but still gain a little until 18 months or so.

These ages line up with guidance from the American Kennel Club, Purina and VCA, which all describe small dogs as mostly grown within the first year and large and giant dogs taking up to two years. If you are curious how your dog's first year compares with a human childhood, see our guide to dog and cat years in human years.

How to estimate your puppy's adult weight

The method our calculator uses

1. Pick the expected adult size class. For a purebred, use the breed standard. For a mixed breed, use the parents if you know them (more on that below).
2. Weigh your puppy and note their age in weeks.
3. Find the typical fraction of adult weight for that age and size in the chart above. Between two ages, the calculator interpolates.
4. Divide the current weight by that fraction, then give or take about 15%.

Example: a 20-week-old large-breed puppy who weighs 15 kg. Large puppies are typically about 52% of adult weight at 20 weeks, so 15 ÷ 0.52 ≈ 29 kg, with a likely range of roughly 25–33 kg.

The estimate is least reliable before 8 weeks, when birth weight and litter size still dominate, and it gets more accurate as your puppy gets older. Re-check every few weeks rather than trusting a single early number.

Popular rules of thumb, and their limits

• Double the weight at 16 weeks. This assumes a puppy is half grown at four months. That is close for medium breeds, but a toy puppy is usually around 70% grown by then (so doubling overshoots), and a large or giant puppy is only around a third to two-fifths grown (so doubling undershoots).
• Weight ÷ age in weeks × 52. This assumes a puppy gains the same amount every week for a year. Growth actually slows down, so the formula overestimates for young and small puppies. For a 12-week-old toy puppy it predicts more than four times today's weight, when about double is more realistic.
• Paw size. Big paws can hint at a bigger dog, but paw proportions vary a lot between breeds and even between littermates. It is a fun guess, not a measurement.

Track your puppy's growth in PetVitals. Log weigh-ins and see the growth chart, with reminders for vaccines and deworming. Seeing the curve over a few months tells you much more than any single estimate.

What affects adult size

• Genetics and breed. This is the biggest factor. Breed standards give a realistic adult weight range.
• Parents' weight. For mixed breeds, the parents are the best clue. Many puppies land somewhere between the two, and males usually end up a bit heavier than females. If the parents are unknown, a dog DNA test can suggest the breed mix and a likely size range.
• Sex. Males of the same breed are often 10–20% heavier than females.
• Nutrition and health. Underfeeding, parasites or illness can slow growth. Overfeeding does not make a dog genetically bigger; it mostly adds fat and, in large breeds, speeds up growth in a way that strains developing joints.
• Neuter timing. Timing can affect growth plate closure and joint health. The American Animal Hospital Association suggests waiting until growth stops (about 9–15 months) for male dogs expected to weigh over about 20 kg (45 lb). The right timing varies by breed and sex, so discuss it with your vet.

Is my puppy a healthy weight?

The number on the scale only tells half the story. Vets use a body condition score (BCS), usually on a 9-point scale where 4–5 is ideal. You can do a quick check at home:

• Ribs: you can feel them easily with a light layer of fat over them, but cannot clearly see them.
• Waist: looking down from above, there is a visible waist behind the ribs.
• Tummy: from the side, the belly tucks up behind the chest.

If you cannot feel the ribs, your puppy is likely carrying too much weight. If ribs, hip bones or the spine stand out clearly, they may be too thin. Puppies often look lanky and awkward in growth spurts, which is normal as long as they are energetic and eating well. A round, bloated belly in a thin puppy can be a sign of worms and is worth a vet check.

Weigh your puppy every one to two weeks in the first months, at the same time of day and on the same scale. Royal Canin's veterinary guidance suggests at least every two weeks while plotting growth charts.

Feeding a growing puppy

• Use a puppy food that matches the expected adult size. Large and giant breed puppies do best on a diet made for large-breed growth, with controlled calcium and energy.
• Do not add calcium supplements to a complete puppy diet. Excess calcium is linked to skeletal problems in large breeds.
• Measure meals instead of free-feeding. VCA notes that portion feeding is the easiest way to keep puppies from becoming overweight, and that moderately limiting energy during growth can lower hip dysplasia risk without reducing final adult size.
• Aim for slow, steady growth, not maximum growth. A lean puppy growing along their curve is the goal.
• Adjust portions as they grow. Use the feeding guide as a starting point and adjust by body condition. Our guide on how much to feed a dog or cat explains how to work out daily portions.

Most puppies move from 3–4 meals a day at 8–12 weeks to 2 meals a day by around 6 months. Small breeds often switch to adult food around their first birthday, while large and giant breeds usually stay on growth food longer; ask your vet when to switch.

When to see a vet

Puppies already visit the vet often for their vaccination schedule, and those visits are a good time to weigh in and ask about growth. Book an extra check if your puppy:

• Loses weight, or stops gaining for more than two weeks while still young
• Drops well below their usual growth curve, or gains much faster than expected
• Becomes ribby or bony, or develops a pot belly
• Limps, has swollen joints or seems stiff, especially in large and giant breeds
• Has ongoing diarrhoea, vomiting or a poor appetite

After the first year, routine checkups usually drop to once a year. Our guide on how often a dog or cat should go to the vet covers the schedule by life stage.

Every method on this page, including our calculator, gives an estimate. Your puppy's own growth curve over several months, plus your vet's hands-on body condition check, is the most reliable guide to how big they will get and whether they are growing well.