How should I describe 2:45?

What is the most common way to express 2:45, using quarter, in the US?

• Quarter of three?
• Quarter to three?
• Quarter till three?

Solution 1:

The data in the Corpus of Contemporary American English shows the most common preposition for 15 minutes before the hour is to.

Solution 2:

I think with the ubiquity of digital clocks, it is much more common for Americans to just say the words "two-forty-five." (I know my teens don't ever say "quarter to" or "quarter after.")

But, just as Brett Reynolds' answer showed, the NGram for "quarter of three, quarter to three, quarter till three (and variations)", using the corpus American English from 1800 to 2008, shows that quarter to three is much more commonly used than quarter of three.

Solution 3:

My first inclination? I thought I'd be likely to say quarter 'til twelve -- but I wasn't entirely certain. So, I pulled a clock from the wall, and surveyed some coworkers. Most of them said "11:45," but then I pressed for an alternative answer. The results of this unscientific poll:

Quarter 'til twelve: 3 respondents 
Quarter to twelve: 1 respondent
Confused stammering: 1 respondent

In the ensuing discussion, one person remarked that, in conversation, what's often spoken is an abbreviated, contraction-like form: quarter t' twelve, where the t' is pronounced with a schwa sound (i.e., with a very quick tuh), where it might be hard to distinguish if the person was intending to say "to" or "'til."

Some footnotes:

1. I think I'd be more likely to speak using the 'til form than write it that way, which might explain why my ears perceive differently than my eyes read.
2. As Jim said in his opening comment, there are several dialects in the U.S., so this might be localized. The one "to" respondent in my survey hails from a different state than the three who said "'til," and he just moved here a couple weeks ago.