This medium-sized nightjar measures 22–27 cm (8.7–10.6 in) in length, spans 45–50 cm (18–20 in) across the wings and weighs 42–69 g (1.5–2.4 oz).
Further standard measurements are a wing chord of 14.7 to 16.9 cm (5.8 to 6.7 in), a tail of 10.5 to 12.8 cm (4.1 to 5.0 in), a bill of 1 to 1.4 cm (0.39 to 0.55 in) and a tarsus of 1.5 to 1.8 cm (0.59 to 0.71 in).
Adults have mottled plumage: the upperparts are grey, black and brown; the lower parts are grey and black.
They have a very short bill and a black throat.
Males have a white patch below the throat and white tips on the outer tail feathers; in the female, these parts are light brown.

This bird is sometimes confused with the related chuck-will's-widow (Antrostomus carolinensis) which has a similar but lower-pitched and slower call.
This medium-sized nightjar measures 22–27 cm (8.7–10.6 in) in length, spans 45–50 cm (18–20 in) across the wings and weighs 42–69 g (1.5–2.4 oz). Further standard measurements are a wing chord of 14.7 to 16.9 cm (5.8 to 6.7 in), a tail of 10.5 to 12.8 cm (4.1 to 5.0 in), a bill of 1 to 1.4 cm (0.39 to 0.55 in) and a tarsus of 1.5 to 1.8 cm (0.59 to 0.71 in). Adults have mottled plumage: the upperparts are grey, black and brown; the lower parts are grey and black. They have a very short bill and a black throat. Males have a white patch below the throat and white tips on the outer tail feathers; in the female, these parts are light brown.
This bird is sometimes confused with the related chuck-will's-widow (Antrostomus carolinensis) which has a similar but lower-pitched and slower call.
Eastern whip-poor-will