The company says it was able to produce the Moto G phones faster than expected. The US launch was initially planned for January. But it is going on sale Tuesday.
The Moto G phone starts at $179 without a contract requirement. That compares with $600 or more that people must typically pay for high-end phones without traditional two-year service agreements.
With the Moto G, Motorola is trying to offer a device that is closer to what's currently available on leading high-end phones, although it won't work on the faster 4G LTE networks.
The version out Tuesday will work only with GSM networks, the type used by AT&T, T-Mobile and most carriers around the world. It won't work with Verizon and Sprint, which have CDMA networks. Verizon says it will offer the CDMA version early next year. There's no immediate word on Sprint's plans.
The phone's 4.5-inch (11.4-centimeter) screen, measured diagonally, is capable of high-definition video, but only at 720p, not at the better, 1020p standard found in leading phones. The resolution is 329 pixels per inch, which is comparable to the 326 pixels in the latest, 4-inch iPhones but short of the 441 pixels in Samsung's 5-inch (12.5-centimeter) Galaxy S4.
The $179 price is for a phone with 8 gigabytes of storage, not the 16 gigabytes typical with high-end phones. A 16-gigabyte version is available for $199. The rear camera can take images at 5 megapixels, which is less than leading phones.
In the U.S., Motorola is targeting so-called prepaid accounts. Under those plans, customers pay for devices up front, but are not tied to two-year service agreements. Credit-challenged customers who don't qualify for traditional plans often sign up for prepaid accounts.
Motorola is owned by Google Inc. Moto G, however, won't get Google's latest Android operating system, Kit Kat, until early next year.
The phone launched two weeks ago. It's currently available in Brazil, Mexico, Chile, Argentina, Peru, Britain, Germany, France and Canada.