It is found in Costa Rica, El Salvador, Guatemala, Honduras, Mexico, and Nicaragua.

A molecular phylogenetic study published in 2014 found that the genus Amazilia was polyphyletic.

In the revised classification to create monophyletic genera, the blue-tailed hummingbird was moved by most taxonomic systems to the resurrected genus Saucerottia.

Their underparts are mostly bright metallic green with dull steel blue undertail coverts.

Their belly has some dull buffy whitish mixed in and their undertail coverts are grayish.

Its head and back are darker green, the rufous or cinnamon patch on the wings is larger, and the undertail coverts are dull steel blue with rich ferruginous edges.

The nominate S. c. cyanura is found in southern Honduras, eastern El Salvador, and northwestern Nicaragua.

It has a large range and an estimated population of at least 50,000 mature individuals, though the latter is believed to be decreasing.