This is a Robin-sized bird at 15-17.5 cm in length, slightly larger than its relative, the Dunnock. It has a streaked brown back, somewhat resembling a House Sparrow, but adults have a grey head and red-brown spotting on the underparts. It has an insectivore's fine pointed bill.
Sexes are similar, although the male may be contrasted in appearance. Young birds have browner heads and underparts.