Online retail spending reached $38 billion this quarter, up 12 percent from a $33.8 billion a year ago according to Comscore. This growth is due to an increase in the number of buyers (7%), transactions per buy (9%) and tempered by a decline in spending per transaction (4%).

According to a ComScore report released today, nearly half of those orders included free shipping, at 47% versus 53% for Q’1 ’11, 49% versus 51% in Q’4 10 (the holiday season) and 41% versus 59% in Q3 ’10.

“A lot of consumers are taking free shipping for granted,” said ComScore Chairman Gian Fulgoni. Indeed the report also came to the conclusion that 61% consumers are “at least somewhat likely” to cancel their entire purchase if free shipping isn’t involved. So have we come to expect free delivery on our gadgets, Christmas sweaters and cookbooks?

As eCommerce hits the highest share percentage its ever seen versus retail ( 8.6% ), the perk of free shipping is a major incentive to buy more, as orders with free shipping average around 30% higher in value those that tack on a couple of bucks for transport.

Those that have Amazon Prime know this instinctively, the proof is in the piles of smiley-faced boxes scattered around your house.