Packet Pair is an end-to-end approach to estimate the capacity of an Internet path. Many studies have shown that such estimation exhibits a lot of bias due to the dynamic cross traffic. In this paper, we propose a novel approach, called Packet Triplet, which uses three back-to-back probing packets - different from two back-to-back probing packets in Packet Pair - to estimate the capacity of a network path. A new filtering technique is also introduced into Packet Triplet to further refine the path capacity estimation approach. The experiments demonstrate that such probing approach is effective under different cross traffic.