What size is a cot bed duvet cover? Rebecca Leonard August 22, 2018 12:49 Updated Follow Our cot bed duvet covers measure 120cm x 150cm. Internal flap measures 40cm. Shop cot bed duvet covers. Related articles What size is a cot bed fitted sheet? What materials are used to make our Poly Cotton bed linen and what are their benefits? Comments 0 comments Please sign in to leave a comment.