What is the impact of the gender pay gap in academia over the course of a career and retirement? To quantify this impact, we used a Canadian post-secondary institution as a case study and simulated the effects of the reported difference in salary across multiple academic career trajectories. A starting wage gap of less than $9,000 resulted in a $300,000-$400,000 gender wage gap over the course of a career, and a further $148,000-$259,000 gender pension gap, for a total gender pension and wage gap of $454,000-$660,000, depending on the rank achieved. Thus, focusing on gender gaps in salary alone leads to a substantial underestimation of the long-term effects of the gender gap.