The most important metric for Apple in the quarter that ended two weeks ago — likely to account for more than half of the company’s revenue for fiscal Q2 2012 — is the number of iPhones it sold from Jan. 1  to Mar. 31.

We’ve polled 48 analysts — evenly divided between professional and independent — and the indies, as usual, have gone considerably further out on a limb than the pros.

The numbers from the two dozen Wall Street analysts we’ve heard from range from a high of 33.1 million from Pacific Crest’s Andy Hargreaves to a low of 26 million, submitted by both Deutsche Bank’s Chris Whitmore and Brian Marshall of the ISI Group.

The average among the Wall Street analysts is 30.5 million, which would represent a year-over-year unit sales increase of  63.8%.

Our pool of independent analysts — an assortment of bloggers, Apple enthusiasts and individual investors — has swelled considerably this quarter thanks largely to the work of Posts at Eventide‘s Robert Paul Leitao. He’s gathered 15 of them at his newly formed Braeburn Group (named after an apple variety with, as he puts it, a “smart and complex flavor”).

The average estimate among the full group of 24 indies is nearly 37.2 million iPhones, which would represent an increase of 99.9% from the same quarter last year. Within this group, the estimates range from a high of 44 million from the Braeburn Group’s Gabriel Dubois to a low of 31.5 million from Bullish Cross‘ Andy Zaky, who has turned somewhat bearish since he launched his hedge fund.

To hedge our bets, we’ve singled out the six analysts who have turned in the most accurate estimates over the past five quarters. Their consensus: nearly 35.1 million units, an increase of 88.5% year over year.

We’ll find out who was closest to the mark when Apple reports its earnings after the markets close on Tuesday, April 24.

Below the fold: The analysts’ individual estimates, with the pros in blue and the amateurs in green.