Male and female American coots are visually similar, but females are typically smaller than males. They both have dark gray to black bodies, a white bill with a frontal shield (a white extension of the bill up the forehead), and lobed feet. During the breeding season, males may have a slightly larger ruff (head plumage).

• Plumage: Both sexes are predominantly dark gray to black.
• Bill and Shield: They share a distinctive white bill with a white frontal shield. The shield can have a reddish-brown spot near the top.
• Size: Males are generally larger than females, with a noticeable difference in body mass.
• Breeding Season: Males may have a slightly larger ruff on their head during the breeding season, which can be used to differentiate them during aggressive displays.
• Other Features: They have red eyes and lobed feet (lobes of skin along the toes, not fully webbed).
• Immature Birds: Juvenile coots are paler gray and have olive-brown crowns.