The ever-growing leakage current of MOSFETs in nanometre technologies is the major concern to high performance and power efficient designs. Dynamic power management via power-gating is effective to reduce leakage power, but it introduces power-up current that affects the circuit reliability. The authors present an in-depth study on high-level modelling of power-up current and leakage current in the context of a full custom design environment. They propose a methodology to estimate the circuit area, maximum power-up current, and minimum and maximum leakage current for any given logic function. Novel estimation metrics are built based on logic synthesis and gate-level analysis using only a small number of typical circuits, but no further logic synthesis and gate-level analysis are needed during the high-level estimation. Compared to time-consuming logic synthesis and gate-level analysis, the average errors for circuits from a leading industrial design project are 23.59% for area, 21.44% for maximum power-up current, 15.65% for maximum leakage current and 6.21% for minimum leakage current. In contrast, estimation based on quick synthesis leads to an 11× area difference in gate count for an 8-bit adder.