The Brown-throated Sunbird is a relatively large, heavy sunbird with a thick beak.Measures 14 centimetres (5.5 in) in length, it has a mass of 7.4–13.5g ,with males averagely slightly bigger than females.The male has green and purple upperparts with chestnut on the wing-coverts and scapulars; it is primarily yellow below. The female has olive-green upperparts and yellow underparts.