Mikey the Border Collie, a happy puppy

How big will my puppy get?

Whether you are shopping for a pet door or just wondering, it’s a common to question: how big will my puppy get as it becomes fully grown? While not an exact science, there are a few different ways to project it reasonably well:

  1. Weigh your puppy
  2. On puppychart.com pick the breed (approximate is ok)
  3. Pick your dog’s birthday (approximate is ok)
  4. Enter the date and weight from the last time you weighed your dog
  5. See the projected adult weight posted.

Alternative options:

  • Look at your dog’s parents or adult siblings
  • For mixed breeds, you can average out each breed to get an idea

One such tool is on the free website PuppyChart.com. PuppyChart  takes your dog’s weight and projects how much their adult weight will be using historical data. We’ve weighed our border collie puppy Mikey frequently since getting her in July so we can look into how quickly into a dog’s life PuppyChart’s projection stabilizes.

Mikey’s Growth Results

When we first took Mikey home, she weight only 8.2 lbs in a collection of fluff and cuteness. At that age (57 days), PuppyChart thought she would be only 29.3 lbs at maturity, which is a bit on the smaller end. Remarkably, even though we weighed Mikey 26 more times her PuppyChart projection remained largely consistent, fluctuating around between 28.9 and 33.6 lbs and usually in the 31-32 range as shown in red in the graph below.

If you have a puppy, estimating their size can be difficult. Here is how we guessed Mikey's size for her pet door

Mikey’s still only a little over 5 months and still has some more growing to do, but so far it really looks like she’s headed to become about 32 lbs. The PuppyChart projection means that even at only 8 weeks, you can get a pretty good idea of how big your dog will grow. What a great way to answer that how big will my puppy get question!

Actual and projected weight growth of Mikey the Border Collie showing her growth approaching expected weight

If your dog is a mix, the question of how big will my puppy be can get more complicated.  You could probably average the projections based on each component to get an idea. Another fun thing you could do with rescues is to work backwards to figure your dog’s actual birthday. If you rescued a dog that was only 20 lbs and later grew to be 65 lbs, you can work backwards to extrapolate that your puppy was about 11 weeks when you got her!

Mixed breeds can be hard to measure so we suggest averaging projections based on their breed!

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