Most puppy growth charts give you a table of pounds by age for one breed. That is useful right up until your puppy is not that breed, or is running a little large, or is a mix.
A percentage chart works better. Instead of asking “how much should my puppy weigh,” it asks “how far through growing is my puppy right now” — and that question has a much more stable answer across breeds.
Percentage of adult weight, by age and size
These figures come from our own growth model, fitted to published breed growth charts spanning Chihuahua to Great Dane. The methodology and its error margins are published in full.
| Age | Toy (6 lb) | Small (16 lb) | Medium (35 lb) | Large (70 lb) | Giant (130 lb) |
|---|---|---|---|---|---|
| 2 mo | 32% | 27% | 23% | 20% | 18% |
| 3 mo | 45% | 40% | 36% | 32% | 29% |
| 4 mo | 58% | 52% | 48% | 44% | 41% |
| 5 mo | 68% | 63% | 59% | 56% | 53% |
| 6 mo | 77% | 73% | 69% | 66% | 63% |
| 7 mo | 83% | 80% | 77% | 74% | 71% |
| 8 mo | 88% | 85% | 83% | 81% | 78% |
| 9 mo | 92% | 90% | 88% | 86% | 84% |
| 10 mo | 94% | 93% | 91% | 90% | 88% |
| 12 mo | 97% | 96% | 95% | 94% | 94% |
| 15 mo | 99% | 99% | 98% | 98% | 98% |
| 18 mo | 100% | 100% | 99% | 99% | 99% |
To use it: divide your puppy’s current weight by the percentage for its age and size. A 20 lb medium-breed puppy at four months is at 48%, so 20 ÷ 0.48 ≈ 42 lb as an adult.
That is the arithmetic our puppy size calculator performs, with two refinements — it solves for the adult weight rather than snapping to a size band, and it blends the result with breed-specific data.
The shape matters more than the numbers
Two things in that table are worth pulling out, because they explain most of the confusion owners have about growth.
Growth decelerates hard. A medium-breed puppy adds 25 percentage points between two and four months, and 7 points between eight and ten. Nothing is wrong at eight months; that is simply what the top of a growth curve looks like.
The halfway point moves later with size:
| Size | Half of adult weight reached at |
|---|---|
| Toy (6 lb) | ~15 weeks |
| Small (16 lb) | ~17 weeks |
| Medium (35 lb) | ~18 weeks |
| Large (70 lb) | ~19 weeks |
| Giant (130 lb) | ~21 weeks |
This is why “double your puppy’s weight at 16 weeks” is roughly right for a medium breed and progressively wrong in both directions. Applied to a Chihuahua it under-predicts; applied to a Great Dane it under-predicts badly.
The underlying biology is consistent: a study of twelve breeds found larger breeds have a longer growth period, not just a faster one.
When growth is complete
Percentages tell you how far along; these windows, from the Purina Institute, tell you when it ends:
| Size class | Adult weight | Growth typically complete |
|---|---|---|
| Toy | Under 12 lb | 6–9 months |
| Small | 13–20 lb | 8–10 months |
| Medium | 20–50 lb | Up to 12 months |
| Large | 50–100 lb | 12–18 months |
| Giant | Over 100 lb | Up to 24 months |
Adult weight generally arrives before skeletal maturity. A large-breed dog can be at its final weight at twelve months and still be filling out in the chest at eighteen. We cover that distinction in when do puppies stop growing.
The part most charts leave out: track the line, not the number
The clinically useful version of a growth chart is not a table of averages. It is a centile chart — the same idea as the growth charts used for human infants.
The reference set is the WALTHAM puppy growth charts, built on Salt et al. (2017) from over six million weight records. They are free, sex-specific, and split by adult-weight category.
The rule for reading them is simple and widely misunderstood:
Which centile your puppy sits on does not matter. Whether it stays on that centile does.
A puppy tracking steadily along the 25th centile is growing normally. A puppy that starts on the 25th and climbs to the 75th over three months is not “catching up” — it is gaining faster than its own trajectory predicts.
That distinction is not cosmetic. A follow-up study tracking dogs to age three found that consistently crossing upward through centiles from around six months of age was an early signal of later weight problems. Owners frequently read exactly that pattern as a thriving puppy.
Giant breeds: no chart exists
If your puppy will finish over about 88 lb, be aware that the evidence runs out.
Salt et al. produced validated centile curves for five size categories and then stopped, in their own words:
The most common breeds in size category VI (e.g. Great Dane, Mastiff and Rottweiler) had widely varying growth trajectories and, consequently, it was not possible to create a growth curve model for this category.
A Great Dane and a Mastiff do not grow alike, so a single chart cannot represent both. Any giant-breed growth chart you find online is extrapolation — sometimes reasonable, but not validated. Treat the numbers as looser than they look, and lean harder on body condition than on the scale.
Worked examples
Percentages are easier to trust once you see them applied.
A Labrador puppy, male, 4 months, 35 lb. Labradors finish in the large range, where four months is about 44% of adult weight. 35 ÷ 0.44 ≈ 80 lb. Measured population data puts male Labradors around 68 lb on average, so this puppy is tracking large — either genuinely a big example of the breed, or slightly ahead of where it should be. Worth watching the trend over the next two months rather than acting on one reading.
A Cavalier King Charles Spaniel, female, 4 months, 8 lb. Cavaliers are a small breed, where four months is about 52%. 8 ÷ 0.52 ≈ 15 lb — squarely inside the breed’s typical 13–17 lb range for females. Nothing to do here.
A Bernese Mountain Dog, male, 6 months, 60 lb. Bernese sit at the top of the large band, where six months is roughly 65%. 60 ÷ 0.65 ≈ 92 lb. Measured data puts male Bernese near 100 lb, so this puppy is a little behind the average and almost certainly fine — Bernese have a long growth tail, and the chart runs out of validated data at this size anyway.
Notice what all three have in common: the number is a starting point for a question, not a verdict. A single calculation that lands 15% off the breed average tells you to watch the trend, not that something is wrong.
What a healthy growth pattern looks like
Beyond the scale, three things are worth checking every few weeks.
Ribs. Under a light press with a flat hand, you should be able to feel the ribs without digging. If you have to push, there is too much cover; if they are sharply visible from across the room, too little.
Waist. Looking down from above, there should be a visible narrowing behind the ribcage. From the side, the belly should tuck up rather than run straight.
Energy and gait. A growing puppy should be springy. Stiffness after rest, reluctance to use stairs, or intermittent limping during a growth spurt are worth raising with your vet — particularly in large breeds, where developmental orthopedic problems appear during exactly this window.
Body condition beats the scale for one simple reason: it does not require knowing what the dog should weigh. It works even when the breed is unknown, the chart runs out, or the estimate is uncertain.
How to weigh a puppy properly
The measurement matters more than people assume, because you are looking for a trend and noise obscures it.
- Same scale every time. Different scales disagree by more than a small puppy’s weekly gain.
- Every two weeks, not every day. Daily weights are mostly gut contents.
- Same time of day, ideally before a meal.
- Small puppies: weigh yourself, then yourself holding the puppy, and subtract. Bathroom scales are unreliable under about 10 lb.
- Write it down. A number in your head is not a trend.
When to talk to your vet about growth
- No weight gain for several weeks in a puppy still under the maturity age for its size
- Steady climbing across centiles, particularly in a large breed
- Falling away from the trajectory it had been holding
- Limping or stiffness during a growth spurt
- Ribs that are highly visible, or cannot be felt at all under a light press
Growth is one of the earliest visible indicators that something is wrong, and most of the causes — parasites, unbalanced nutrition, some congenital conditions — respond far better to early intervention.