GrowthGuide
Mixed-breed puppy size: parents, DNA tests and paw myths
The question
Without a breed, how do I estimate my mixed-breed puppy’s adult size?
Short answer
Start from your puppy’s own weight and age: that is the route the growth data support. The parents’ adult weights can help you pick a size class, and some DNA tests report the company’s own size estimate, but we found no published accuracy figures for either — and no study supporting paw size.
Updated · sources read · Data and sources →
A mixed-breed puppy doesn’t come with a size label, and the guesses you hear — from the shelter card, the paws, the parents, a DNA kit — often disagree. The good news is that the most useful evidence is already in your hands: your puppy’s weight and age.
This guide ranks the options by what the evidence supports. Every estimate below was computed on October 7, 2026, with the same code our calculators use, from our summaries of the open CC BY 4.0 data behind a 2017 U.S. study of more than 6 million young dogs.
Start with your puppy’s own weight and age
Growth-based estimates need a size class, because a toy puppy and a giant puppy are at very different points of their growth at the same age. Without a breed, the class can come from the puppy itself. Our calculator tries each of the six size classes and keeps the one whose predicted adult weight falls inside that class’s own weight band. Some examples:
| Puppy today | Class it settles on | Central adult estimate | Middle half |
|---|---|---|---|
| 1.5 lb at 12 weeks | I (under 6.5 kg / 14.3 lb) | 3.9 lb | 3.3–4.7 lb |
| 8 lb at 12 weeks | III (9–15 kg / 19.8–33.1 lb) | 25 lb | 21–29 lb |
| 15 lb at 16 weeks | IV (15–30 kg / 33.1–66.1 lb) | 36 lb | 32–41 lb |
| 45 lb at 26 weeks | IV (15–30 kg / 33.1–66.1 lb) | 65 lb | 60–72 lb |
One honest caveat. The 2017 standards were built from dogs of a set of common breeds; the authors excluded mixed-breed dogs. Their 2020 follow-up placed mixed-breed dogs in a size class by their final adult weight when it was known. So the growth pattern of each class is well measured, but no study we found has tested how well these estimates work for mixed-breed puppies specifically. Treat the middle-half range as the answer, not the single number.
Using the parents’ weights
If you know the adult weights of both parents, they can help choose the class. Our calculator averages the two and uses that weight’s class; it doesn’t try to predict the adult weight from the parents directly, because we found no validated way to blend two parents into one puppy.
Here is how that works for a male puppy whose parents weigh 35 lb and 40 lb as adults:
- Average of the parents: 17.0 kg (38 lb), which falls in class IV (15–30 kg).
- The puppy today: 15 lb at 16 weeks.
- Share of adult weight a class IV puppy typically has at 16 weeks: 41%.
- Estimate: about 36 lb (16.4 kg), with a middle half of 32 to 41 lb and 8 in 10 between 29 and 47 lb.
When the parents are very different sizes — say 10 lb and 60 lb — the average still lands in a class (class IV here, at 35 lb), but our calculator adds a plain warning that mixed sizes are hard to predict. In that case, rely on your puppy’s own weigh-ins over the next few months more than on the parents.
How much the size class changes the answer
The class matters, but less than people fear in the middle sizes. Here is the same 15-lb puppy at 16 weeks run through every class:
| Size class | Central adult estimate | Middle half |
|---|---|---|
| I | 30 lb | 26–35 lb |
| II | 30 lb | 27–34 lb |
| III | 33 lb | 29–38 lb |
| IV | 36 lb | 32–41 lb |
| V | 37 lb | 33–42 lb |
| VI | 42 lb | 38–48 lb |
Neighboring classes give overlapping ranges, so a class that is one step off moves the estimate a few pounds, not dozens. The choice matters most at the extremes: if your puppy may become a giant, the class VI estimate is noticeably higher, and growth over 40 kg (88.2 lb) is less predictable — the 2017 standards do not cover it.
DNA tests
Some dog DNA tests now report a size estimate. On October 7, 2026, Embark’s product page listed a predicted adult weight among the results of its breed and health test, and Wisdom Panel’s page listed an ideal weight range, described as a recommendation based on breed and genetic tests. These are the companies’ own descriptions. Neither page we read gave an accuracy figure for the weight estimate, and we found no published study that measures one.
If you already have a DNA report with a predicted adult weight, you can use it to pick the size class in our calculator, and then let your puppy’s weigh-ins confirm or correct it. Without published accuracy figures, the test’s weight estimate is best treated as one more clue.
Paw size
Big paws on a puppy are a favorite clue, and they are fun to watch. As a predictor of adult weight, though, they have no evidence behind them. On October 7, 2026, we searched Europe PMC, a large index of biomedical research, for studies of puppy paws and adult weight or size: of 147 records, the 100 we screened by title included none that tested paw size as a predictor. Paws are part of the puppy’s growth, not a forecast of it.
This is general information, not veterinary advice — talk to your vet if you are unsure how your puppy is growing.
Next step
Weigh your puppy, note the exact age in weeks, and enter both in the puppy weight calculator without a breed, so it estimates the size class from the weight — or with the parents’ weights if you have them. Weigh again every few weeks and add each result to the puppy growth chart; a run of estimates that agree is worth more than any single clue. For the full method, see how big will my puppy get, and for why the popular doubling rules miss, see puppy weight rules of thumb.
Calculators for this guide
- Puppy weight calculatorYour puppy’s likely adult weight from age, weight and breed or size, with the range half of puppies like yours end in.
- Puppy growth chart & weigh-in trackerUp to 12 weigh-ins on centile lines from open veterinary data, with the weekly gain and a flag when the curve crosses lines.
Sources
Each source was read on the date shown. When one changes, this guide and its date change with it.
- Growth standard charts for monitoring bodyweight in dogs of different sizes
- Growth standard charts for monitoring bodyweight in dogs of different sizes - SUPPORTING DATA
- Comparison of growth patterns in healthy dogs and dogs in abnormal body condition using growth standards
- Breed + Health Dog DNA Test Kit (product page)
- Dog DNA Tests (product page)
- Literature search: (puppy OR puppies) AND (paw OR paws) AND adult weight, adult size or body weight
Data licences
Growth bands derived by Puppy Scale from Salt C et al. (2017), PLOS ONE 12(9):e0182064, data: University of Liverpool DataCat 377, licensed CC BY 4.0. Our tables are empirical summaries, not the published model curves. Changes: see the method.
Printed from Puppy Scale (puppyscale.com/guides/mixed-breed-puppy-size/) · updated October 7, 2026 · general information, not veterinary advice.