- This paper addresses the problem of true delay estimation during high level design. The existing delay estimation techniques either estimate the topological delay of the circuit which may be pessimistic, or use gate-level timing analysis for calculating the true delay, which may be prohibitively expensive. We show that the paths in the implementation of a behavioral specification can be partitioned into two sets, SP and UP. While the paths in SP can affect the delay of the circuit, the paths in UP cannot. Consequently, the true delay of the resulting circuit can be computed by just measuring the topological delay of the paths in SP, eliminating the need for the computationally intensive process of path sensitization. Experimental results show that high-level true delay estimation can be done very fast, even when gate-level true delay estimation becomes computationally infeasible. The high-level delay estimates are verified by comparing with delay estimates obtained by gate-level timi...