Mind Your Ps and Qs

There are a couple of popular explanations for the phrase, “mind your Ps and Qs,” which is accepted as meaning “mind your manners,” or “be mindful of your behavior in certain circumstances.” (For example, “my granny is very proper, so mind your ps and qs around her.”) But where does the expression come from?

One popular derivation is that pub owners in Britain kept tabs on their customers by writing P (for pints) or Q (for quarts) on a slate. If customers were rowdy or hadn’t paid up, the pub owner might yell, “mind  your ps and qs.” But I’ve also read that pub owners would more likely have used a single stroke for a pint & two for a quart, a system still in use in some places. And according to Snopes, “At the time the saying became part of the English lexicon, beer wasn’t vended in pubs by the pint or quart. Instead, it was drawn from kegs, with patrons charged by the glass or tankard. Vendors therefore would not have utilized chalked tote boards scrawled with p’s for ‘pints’ and q’s for ‘quarts’ in an effort to keep track of how much customers owed.”

The other widely accepted explanation comes from the era of “hot metal” typography.” In letterpress printing, words were composed using individual letters made of metal, with each letter facing backwards. This could be confusing, especially in the case of the mirrored lower-case letter pairs of  p and q, and b and d. So the advice, especially given to novice printers, was “mind your p’s and q’s.”