In this paper we characterize the validity of the Hardy-type inequality p,u,(0,t) q,w,(0,∞) ≤ c h 1,v,(0,∞) , where 0 < p < ∞, 0 < q ≤ +∞, u, w and v are weight functions on (0, ∞). It is pointed out that this characterization can be used to obtain new characterizations for the boundedness between weighted Lebesgue spaces for Hardy-type operators restricted to the cone of monotone functions and for the generalized Stieltjes operator. MSC: Primary 26D10; 46E20