How many times does a heart beat in a lifetime?

Question

Estimate how many times a human heart beats in a lifetime. State your assumptions and give an order-of-magnitude answer. Then compare with a mouse (heart rate about 500 per minute, lifespan about 2 years) and an elephant (about 30 per minute, 60 years).

Accepted Answer

About 3 billion. The chain. A resting heart rate is about 70 beats per minute. There are 60 × 24 = 1,440 minutes in a day, so about 100,000 beats per day (70 × 1,440 = 100,800). Times 365 days: about 37 million beats per year. Times an 80-year life: about 3 billion beats. Using the shortcut "a lifetime is about 2.5 billion seconds" and "a bit more than one beat per second" gives the same answer. The animals. The mouse: 500 × 1,440 = 720,000 beats per day, times 730 days, about 525 million. The elephant: 30 × 1,440 = 43,200 per day; × 365 × 60 = about 950 million. Humans, at about 3 billion, a…

How many times does a heart beat in a lifetime?

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