  Despite quantum tunneling has been studied since the advent of quantum
mechanics, the literature appears to contain no simple (textbook) formula for
tunneling in generic asymmetric double-well potentials. In the regime of strong
localization, we derive an succinct analytical formula based on the WKB
semi-classical approach. Two different examples of asymmetric potentials are
discussed: when the two localized levels are degenerate or not. For the first
case, we also discuss a time-dependent problem showing quantum Zeno effect.
