Have you heard the popular myth that one human year is equal to seven dog years? This would mean that a dog that is one human year old (365 days) is developmentally about the same as a human child who is seven years old.

Who came up with this idea? We’re fairly certain it wasn’t a dog. Not only do dogs not wear wristwatches, but most dogs we know seem quite unconcerned with the time. In fact, most dogs we know seem blissfully unaware of whether it’s Monday or the weekend!

The idea of a “dog year” probably came about as a result of the fact that dogs develop at a different rate than human beings. A one-year-old child still relies on its parents for nearly everything. A one-year-old dog (in human years), though, does behave much more like an older child.

These developmental differences can be seen throughout a dog’s lifetime. If you and a dog are born on the same day, the dog will develop and age much more quickly throughout its lifetime than you will.

For example, when you hit your teenage years, the dog will be quite advanced in age. As you’re ready for high school, the dog will be ready for the retirement home! If it helps, you can also think of it this way: a dog’s lifespan is a lot shorter than yours (maybe 15 years compared to 75 or more for you), so that means a dog ages much more quickly in the same amount of time.

How old a dog will live depends upon many factors, including its particular breed and size as an adult. Small dogs often live 15 years or more. Medium and large dogs tend to live shorter lives (10-13 years). Giant dog breeds, like mastiffs, might only live 7-8 years.

Given these differences in life expectancy based upon breed and size, you can see that a simple formula of one human year being equal to seven dog years would not be accurate. Although dog experts do not agree on a standard formula, there are some similarities in the ways different people think about things.

The most accurate calculation of dog years must take into account the particular breed and size of the dog in question. You can do research online to find special calculators that will estimate a dog’s age based upon its size and breed.

Others use a variable formula that reflects the belief that the first two years of a dog’s life are approximately equal to 10-11 years each, with each year thereafter being equal to about four human years. Over time for many dog breeds, this variable formula might average out to the common belief that one human year is equal to about seven dog years.

The variable formula reflects the fact that dogs develop quickly early in their lives. After the first couple of years, most dogs are fully grown and develop more slowly thereafter. The variable formula still does not take into account particular breed and size information, though.

Dog experts know that some breeds tend to live longer than others. As mentioned before, a dog’s adult size is also an important factor. If you take these factors into account, a sliding scale for each dog is the only accurate way to estimate a dog’s age in human years.

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    • Hi there, Julia! It’s WONDERful to hear from you today! Thanks so much for sharing your thoughts about dog years and THANKS for visiting Wonderopolis today! :-)

  1. Dear Wonderopolis,
    Hi it’s Leilani, my doctor said I might have to go back to the hospital, wish me luck. I have a doctor’s appointment today!!! Oh, and I think today’s wonder was soooo cool. It might be because I have three dogs!
    Bye,
    Leilani

    • We think those are three really lucky dogs to have such an AWESOME friend like you to play with every day, Leilani! We hope your doctor’s appointment went well today and that you get better SUPER soon! We care about you and all of our Wonder Friends! :-)

  2. While I was reading the article, I just discover and learn that Snowy my dog is about 6 years old and my brother’s dog Ramona is about 3 1/2 years old. :)

    • Thanks for sharing how old Snowy and Ramona are, Carlos! That’s really cool! We’re glad you stopped by today’s Wonder and learned some fun new facts about dog years with us! :-)

    • Well, we think YOU ROCK for leaving us such a super cool comment, Julie! Thanks for being a GREAT Wonder Friend and letting us know you learned something new by WONDERing in Wonderopolis today! :-)

  3. This wonder was great. I have two dogs and always wondered how old they really were, and now I know. So thanks for that! I also loved the video of the cute puppy. It’s amazing how much it can change in 8 weeks. Thanks again!!

    • Thanks for sharing about your two dogs, boyWONDER, and THANKS for sharing another AWESOME comment with us! We’re happy you explored TWO Wonders in Wonderopolis today and left us a message about your connection with each one! YOU ROCK! :-)

  4. This was such a great wonder because I am always asking my parents, “How long is a dog year?” and they say,”I don’t know.” Now, I can TELL them what the answer to that question is. Also, I have a cool idea for Wonderopolis. I WONDER if you could make a book out of all these wonders, like, ‘663 wonders of the day’ (you’ll be up to 500 by the time you’d publish it). What do you think? Thanks for the amazing wonder!

    • WOW, Lucie, we love that you can answer that question now! WONDERing is so much fun and we always love new and exciting ideas! It’s great to hear how much you’ve been WONDERing about new things, like a Wonder book! Thank you for sharing your GREAT Wonders– you ROCK! :)

    • Great question, Dezi! We appreciate your comment, too! Our Wonder Friends are moving… and our comments are out of order! We are sorry for this mix-up, but we’ll have our things sorted out soon. In the meantime, we Wonder if you learned anything new about cavities?! :)

  5. I have a dog. Dogs are sooo fun and cute. Every time I see a dog, on let’s say a walk in the park, I get the urge to want to pet it. My favorite is a border collie.

    • We sure agree, Tyler J! We are all dog lovers here at Wonderopolis, even though some of us are allergic! However, we always smile when we see a fun, lovable pup! :)

    • Happy belated birthday to your pup, Joey! If we assume that a one-year-old dog is the same age as a 7 year-old child, your dog would be 84 years old in human years! You are very close- great work! :)

    • Thanks for sharing your enthusiasm, Kelsie! We’re glad you’re WONDERing with us today! Say hi to Sammie and Loucie for us! :)

  6. I LOVE dogs. I’ve always wondered how much is a dog year is and now I know!!! I have two dogs Foorest and Jenny.

    • We love your bow-wow enthusiasm, Sarah! We’re glad you learned something new with us– now you can celebrate your dogs’ ages on their birthdays! Say hi to Foorest and Jenny for us! :)

    • Hey there, Jeana! Thanks for sharing your comment about how important your dog is to you! We love our pets here at Wonderopolis, and we always enjoy spending time with them. It’s important to take great care of our pets so they can live long, healthy and happy lives! :)

  7. When I’m an adult, I wish to get a small dog breed. I keep trying to write a story about dogs living forever. It’s not working though…
    I still have many questions about dogs and I hope you can answer my questions!!!

    • Hey there, Jenna, we are so glad you shared your comment with us today! It’s AWESOME that you are in the process of writing a story about dogs’ lives! We are so proud of you, and we know it can be tough to write your very own story. Stick with it, and keep WONDERing! We know you’ll be a fantastic author! :)

    • How neat, Wonder Friend Spedy! We love learning about all our Wonder Friends’ furry friends! What kind of dog do you have, Wonder Friend? :)

  8. What am I in for? My dog is 10 months old, and I haven’t considered having him neutered (I think he’s too young). What are your thoughts? Yes, this is my first dog.

    • Hi Domino’s Mom! Thanks for WONDERing with us! We don’t think that is too young to get your dog neutered but that is a preferential choice up to the dog owner! What kind of breed is your dog? We bet that he or she is a lot of fun! Thanks for WONDERing! :)

    • Thanks for commenting today, Wonder Friend Ninja pig. You might want to go back and re-explore the Wonder if you didn’t understand it. :)

  9. I learned a lot a about dog years working on this post. There are a few different theories, but I found that my husky shiba inu mix was landing somewhere 21-24 at 2 human year. I originally thought we should be having a Bark-Mitzvah for her bday… but I guess a bar crawl would have been more in line for her age.

    • Thank you for sharing your personal connection to this Wonder of the Day, DINKSplusDog! We appreciate you, Wonder Friend! :)

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Have you ever wondered…

  • How long is a dog year?
  • Do all breeds of dogs age at the same rate?
  • What factors affect how dogs age?

Wonder Gallery

Try It Out

While it might not be totally accurate, it can still be fun to calculate your dog’s age in human years or your own age in dog years. Jump online and check out the fun Dog Years Calculator and let it do the math for you!

When you’re finished, think about the major milestones your dog (if you have one) has already passed. Has he graduated from high school yet? Can he vote? What job would he have if he was in the workforce?

Draw a funny picture of a dog doing something a human of the same age might do. Share your picture with your Wonder Friends by posting it on Facebook. We can’t wait to see what wild and crazy things you have your dog doing! Here’s a fun video clip to inspire your creative thinking.

Still Wondering

In National Geographic Xpeditions’ Geographical Dog Show lesson, children learn the theories of how dogs were domesticated from wolves and the reasons why people subsequently bred dogs living in different places to do different tasks.

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age  animals  development  dog  human  lifespan  time  year 

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