The generally accepted rule for dog maturity has always been: under 1 year old is a puppy, anything older is an adult dog. But recent research has found this isn’t quite true.

Smaller dogs reach maturity faster than large dogs, with some larger dog breeds taking nearly twice as long to reach full maturity.

A recent survey of 1,000 puppy owners in the United States by Purina found that very few were aware of these differences. Most noticeably, a whopping 92% of large breed owners didn’t realize their dogs might need to be fed puppy food for up to two years.

In case you’re among the more than 50% who aren’t aware how breed and size affect maturity (we didn’t know!), here’s when you can expect your fur baby to reach full adulthood.

Dogs Less than 30 Pounds

Toy and small breed dogs that weight less than 30 pounds can reach full maturity any time between 9 and 12 months of age. Check with your vet but you’ll probably want to switch your teeny Affenpinscher over to adult food before she reaches a year old!

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Dogs Between 30 and 80 Pounds

Medium breed dogs come the closest to the traditional viewpoint that 1 year is the transition from puppy to adult, but even then, some medium breeds can take up to 16 months to mature.

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Does your dog behave? It not, you’ll want to read about the 9 mistakes dog trainers say you’re making.

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Dogs More Than 80 Pounds

Large dogs and giant breeds that typically weight more than 80 pounds can take up to a full 2 years to reach maturity. Pet parents of these oversized puppies will want to keep them on puppy food for longer.

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