"penultimate", "last but one" or "second to last"? Which is more common?

Question

Some say they rarely hear the word "penultimate". They say "second to last" is much more common. But Google Ngram shows that "penultimate" is 10 times more common than "second to last" and "last but one". Which word is actually more common? Which word is most understandable to most people?

Answer 1

In my own experience, which contradicts your Ngram search, is that "second last", "second to last" and "next to last" are the most common.

"Penultimate" is used in technical situations, like scientific descriptions.

"Last but one" feels British to me (a Canadian), and I rarely hear it.