The American goldfinch is 4 to 5 inches long. It is recognizable by the bright yellow color which is very bold in summer, although less strong in winter and in females. There is also a distinctive black and white barred pattern on the wings.

This finch has an undulating or looping flight, and a breeding male does an exaggerated flight which has deep loops. It has a canary-like song.

The goldfinch feeds mainly on seeds, but also eats insects and berries. It does not nest until much later in the summer than most birds, a time when there are plenty of seeds available.