I find some numbers very useful.
From pages 12 and 13 in Concealed Carry Permit Holders Across the United States: 2021 (alternate link here):
There are three relevant sets of numbers from the Pew survey:
— 30% of American adults say that they own a gun.
— 72% of the people who own a gun, say they own a handgun or a pistol.
— 11% of handgun owners say that they carry all the time, 26% say they carry most or all the time, and 57 percent say that they carry at least some of the time.
With a little multiplication, we find that:
— 2.4% say that they carry all the time.
— 5.4% carry most or all the time.
— 12.3% carry at least some of the time.
To summarize, the total number of permits in the US is at least 21.52 million. Add in people who legally carry without a permit, and the number clearly becomes much larger. While 8.3% of the adult population has permits, the percentage of Americans who say that they carry most or all the time is about 5.4%.
What does this mean in practice? It means that in most places where people are allowed to carry a concealed handgun, there will be someone carrying a concealed handgun. If the probability that any one person has a concealed handgun permit is 5.4%, in a room with 10 people (assuming that the probabilities are independent), the probability that at least one person will have a permitted concealed handgun is 43%. In a room with 20 people, that probability goes up to 67%. With 40, that probability rises to 89%.
I usually express it a little differently. I would translate and distill the numbers above into, “On average, about one out every 19 people you pass on the street is carrying a firearm.”