As the release of the iPhone 6 approaches, consumers are preparing to trade-in their old iPhones just in time for an upgrade. Because the iPhone 6 is a new form factor, NextWorth expects to see twice as much trade-in volume on NextWorth.com in comparison to the launches of the 2013 iPhone 5s/5c. Below is a look at how the past sales figures compare to trade-ins at NextWorth. In 2011, the iPhone 4s sold approximately 4 million units in its first weekend. In its first weekend in 2012, the iPhone 5 sold nearly 5 million units. Last year, the iPhone 5s and iPhone 5c combined to sell 9 million units in the first weekend. The steady increase of first weekend sales each year suggests that the iPhone 6 and its numerous upgrades could expect a big first weekend, potentially reaching 10 million units. As far as trade-ins go, historical results show a 105% increase in trades when Apple introduces a new form factor, compared a much smaller change when they introduced an “S” version. The visual below shows NextWorth’s trade-in volumes during the previous launches, and the estimated trade-in expectation for the upcoming iPhone 6 release. Although there is not a noticeable correlation between the sales and trade-ins of previous iPhones, both numbers have increased since the iPhone 4s in 2011. With dramatic changes rumored with the iPhone 6 release, expectations are at an all-time high for sales and trade-ins over the next month.