Get the most money on your iPhone trade in

HOUSTON (KTRK) -- The new iPhone 6 and 6 Plus will be on store shelves soon, and many people are looking to unload their old phones for the latest technology.

The launch of a new iPhone model traditionally causes major depreciation in old iPhone pricing. So what's the best way to get the most money for your old iPhone?

USell.com, an online marketplace for used gadgets, recently examined thousands of used iPhone sales last year and gathered some useful statistics.

Two weeks after a new iPhone launch, old iPhones lose about 11 percent in value. Four weeks after a launch, old iPhones depreciate about 15 percent. If you wait six weeks after launch, the old iPhones go down in value about 18 percent. By week seven, old phones are worth about 21 percent less.

ABC-13 checked out how much we would get now for a 32 GB AT&T iPhone 5C with a cracked screen.

At USell.com, the cash price offer was quoted $42.25, and you can lock in that price for 30 days. There is free shipping and $10 extra for referring a friend who uses the service.

Gazelle.com quoted us $50 for the same phone. They also offer free shipping and $10 for referrals, and the price is locked in for 30 days.

When we used iCracked.com, we were quoted $75, over $30 more than USell.com. The only catch is you have to send in the phone now with their express service, and they specialize in cracked phones.

BestBuy.com also buys phones, but when we put in our phone's specs, we were quoted a trade in value of $0!

You will likely make the most money by using sites like eBay and Craig's List, but you run the risk of dealing with potential scammers. You'll also have to ship the product.

No matter which route you choose, you'll make the most money of unlocked phones with more memory. Unlocked phones mean they can work with any cell phone carrier.