How Big is a Blue Whale’s Heart?


You’ve probably heard claims that a blue whale’s heart is the size of a car, and that people could swim through their aortas. Well . . . (BBC)

Size yourself up to a blue whale with our activity.

Teachers, scroll down for a short list of key resources in our Teachers’ Toolkit.

Discussion Ideas


  • The 400-pound heart of a 40,000-pound animal is still pretty big! (Even though the heart is only about 1% of the whale’s body weight, it’s still the biggest on the planet.) How big is the heart of the world’s largest terrestrial (land-loving) creature? How big is your own heart? How does it compare to the size of a blue whale’s heart?
    • African elephants are the largest terrestrial creatures on Earth. Their round-shaped hearts weigh about 30 pounds.
      • A blue whale’s heart weighs about 14 times as much as an elephant’s heart.
      • The heart makes up about 5% of an elephant’s weight.
    • A human heart weighs about 10 ounces. There are 16 ounces in a pound. Do the math to compare its size to a whale heart—don’t worry, it isn’t hard:
      • 16 ounces in a pound, so 400 pounds is 6400 ounces. (400*16)
      • Now divide that by 10, the weight of a human heart. (6400/10)
      • A blue whale’s heart weighs about 640 times as much as a human heart.
      • The biologist in the video said it took 4 people to remove the heart from the whale’s chest cavity. Your own heart is much more delicate: It makes up less than half a percent of your body weight. If you’re a kid, your heart is about the size of your fist. If you’re an adult, your heart is about the size of two fists. Luckily, we have a nice, strong rib cage protecting this vital organ.


  • So a whale’s heart is not the size of a car. The blue whale’s heart needs a better metaphor! What else weighs about 400 pounds?


  • How did the Royal Ontario Museum get a hold of the blue whale’s heart?
    • Nine big blue whales washed up the idyllic shores of Trout River, Newfoundland, last year. Read this blog post and watch the video below to see how scientists worked with good-natured local “people of the sea” to recover the whale.
      • Warning: Marine biology is messy. This is delightfully gross and graphic stuff—the clotted blood starts to flow at about 1:50—and you’ll be happy your computer doesn’t have smell-o-vision.



BBC: See the world’s biggest heart

Nat Geo: Size Me Up—to a Blue Whale!

Nat Geo: What is a blue whale?

Nat Geo: Beached. Blue. Bloated.

Royal Ontario Museum: Blue Whales

19 thoughts on “How Big is a Blue Whale’s Heart?

  1. Size and weight are different things. A golf cart is definitely closer in size than a Harley or an oil drum. Akshay, I’m in the US and would also like to change it. I think most people’s trepidation probably stems from having to do conversions, but if everything was published, sold, etc, I think we would adjust very quickly

    1. Good morning, and thanks for reading!

      We cannot speak for NOAA, but our own sources (largely, the PBS documentary and the Royal Ontario Museum) are linked in the post.

  2. Why do you talk about “size” (volume) and then go on to talk about weight? You’re comparing metal to flesh.

  3. Informative article, but honestly, when are you Yanks going to switch to metric and join the rest of the world?
    So tired of 1.6 and 2.2 multipliers.

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