# Average number of arms in the United States: limbs, not firearmsOctober 28, 2023 3:45 PM   Subscribe

What is the average number of arms humans living in the United States have? Or how many Amerians have less than two arms?

Presumably the average is less than two, with people born without one or both arms and amputations far exceeding people born with extra arms.
posted by Chrysopoeia to Science & Nature (5 answers total) 2 users marked this as a favorite

You're goimg to have some issue with how to count partial arms. Does it count as a full arm as long as there's an elbow? Or do you do decimals in counting?
posted by DebetEsse at 4:30 PM on October 28, 2023 [1 favorite]

Here are sources that will allow you to at least get a decent estimate of the number of people missing all or part of an arm:

* Estimating the prevalence of limb loss in the United States: 2005 to 2050

* Limb amputation and limb deficiencies: epidemiology and recent trends in the United States.

* Limb amputation and limb deficiency: epidemiology and recent trends in the United States

* Epidemiology of limb loss (full text link)

What makes it hard to calculate the exact statistic you are interested in, is that most of these sources do not break out in detail the exact type of injury or loss - and particularly, they don't give exact breakdowns of upper limb vs lower limb loss. So you would have to dig a bit deeper to find out those exact numbers.

So the first source calculates that 1 in 190 Americans is currently living with loss of a limb. However, that includes both upper and lower limbs.

The last source summarizes limb losses due to various sources. It states that most limbs -by quite a large percentage - are lost due to peripheral artery disease and diabetes. And most of those losses are lower limbs.

For trauma and congenital losses, most are upper limbs. However - again - these are a relatively small minority of all losses.

Putting those two facts together means it is quite hard to estimate what percentage of the people missing limbs are missing upper vs lower limbs.

Taking a wild-ass guess, let's say 2/5 of limb losses are upper limbs. That means that 1/425 Americans is missing an upper limb (or part of it - many of the congenital losses, and some of the others, are just part of the arm, part of the hand, etc. Also of course a few people have losses to BOTH arms.). But plowing ahead regardless of those significant issues, if 1/425 of the population is missing one arm, that means that on average people have 849/425 arms.

In decimals that is an average of 1.99765 arms per person.
posted by flug at 8:23 PM on October 28, 2023 [8 favorites]

This chart from the Amputee Coalition estimates that 35% of limb losses are upper limbs.

However, it's hard to tell whether they're referring to amputations only or also including people born without limbs. At the top of the chart, it refers to their trying to raise awareness of people with both limb loss and limb difference, so they're obviously not only concerned with amputees.

The CDC estimates that 1 in 1900 babies are born with "limb reduction." I suppose you could guess that 35% of those are born without upper limbs, but that still wouldn't differentiate between people born without one arm and without both arms. Plus "limb reduction" seems pretty broad.
posted by FencingGal at 8:45 PM on October 28, 2023

Best answer: So the first source calculates that 1 in 190 Americans is currently living with loss of a limb. However, that includes both upper and lower limbs.

1 in 190 people missing a limb would mean that around 1.6 million people in the US are missing a limb given there are 320 million people in the US. So if 35% of those missing a limb are missing an arm, then that's 598k. So 319,500 have 2 arms and 600k have one arm (we are just going to presume no one has more than 2 arms). So 639m + 600k = total number of arms. So the average is 1.999 arms per person.
posted by The_Vegetables at 7:31 AM on October 30, 2023

Best answer: Also, if every single one of the one armed people actually had zero arms, then the ratio would be 1.998 arms, ie: the number of people with one or less arm is dwarfed by people with exactly two.
posted by The_Vegetables at 8:54 AM on October 30, 2023

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