Dear heart, at some point we will muster the fortitude to make a chart listing all the equivalent measures we can think of, but for now, yes, .25, or 25%, means a quarter of something – in this case, a cup. Point-five is the same as 50%, and refers to half a cup.

By the same cup-based logic, .75 is three-quarters of a cup, .33 is one-third of a cup, and .66 is two-thirds of a cup. We can't imagine that you'd see any other decimal-based fraction in your recipes. Point-125 is an eighth of a cup, but your recipe writer is just cruel if he or she used that!

It is a quite unusual in any event to see decimal fractions with English or American measures, but you see it all the time with the metric system. The more we find and use international recipes on the Internet, the more comfortable we're going to have to get with decimals.