This paper proposes a new voltage stability index (VSI) that has a more or less linear characteristic, and thus can provide better estimation of the distance to voltage collapse. It requires only the normal power flow solution and the type-1 low voltage solution of the critical or weakest bus of the system. The effectiveness of the proposed VSI in estimating the distance to voltage collapse is tested on a 5-bus system and the IEEE 14- and 30-bus systems. The results obtained through the proposed VSI are then compared with those found by other methods, as well as with the corresponding actual values found by repetitive power flow simulations.