Application of logical effort on transistor-level analysis of different 64-bit adder topologies is presented. Logical effort method is used to estimate delay and impact of different adder topologies and to evaluate the validity of the results obtained using logical effort methodology. The tested adder topologies were Carry-Select, Han-Carlson, Kogge-Stone, Ling, and Carry-Lookahead adder. The quality of the obtained estimates was validated by circuit simulation using H-SPICE for 1.8V, 0.18μm Fujitsu technology.