In this paper, we propose a new exact closed form mutual inductance equation for on-chip interconnects. We express the mutual inductance between two parallel rectangular conductors as a weighted sum of self-inductances. We do not place any restrictions on the alignment of the two parallel rectangular conductors. Moreover, they could be co-planar or reside on different layers. Most important, experimental results show that our formula is numerically more stable than that derived in [2] for long parallel on-chip interconnects.