The Trust Equation is a formula created by Charles H Green, Rob Galford and David Maister in their book “The Trusted Advisor”. The equation is T = (C + R + I)/S where T is Trustworthiness, C is Credibility, R is Reliability, I is Intimacy and S is Self-Orientation. The equation is based on earlier work from Green and Galford in their time at the Mac Group and Gemini Consulting.