Addressed here Is the problem of computing accurate time-to-go estimates, which is an important issue in implementing various optimal guidance laws developed for missiles of time-varying velocity. A recursive time-to-go computation method which updates the time-to-go in a noniterative way Is presented. The recursive method includes an error compensation feature which explicitly computes the time-to-go error produced by non-zero initial heading errors. The proposed method is simple and straightforward to implement for any missile velocity profiles. Various numerical examples show that the proposed method works effectively for optimal guidance laws as wen as proportional navigation and augmented proportional navigation.