Loosely the main points are that the rate falls off exponentially with the &quot;width&quot; of the barrier, and that energy is still conserved (you can say the particle &quot;must have&quot; had more energy at some point because it crossed the barrier, but you&#x27;ll never observe it with more energy than it has). For more precise answers, just plug the potential you&#x27;re trying to tunnel through into the Schrödinger equation.