This paper develops a simple asphalt pavement field aging model using IDEAL-CT data from 24 field sections from seven field projects that were monitored for 1–4 years each. Field distress surveys were conducted, and field cores were procured and tested in the laboratory approximately every 12 months for each field section. The model predicts IDEAL-CT parameter l75/ m75 (mm2/kN) from the post-peak load–displacement curve. An R2 of 0.91 was achieved when comparing predicted values to measured values indicating that this ratio behaves predictably with field aging. A good correlation is also seen between this ratio and measured field cracking data, making it an excellent candidate for evaluating pavement cracking performance with field aging. This simple model has promising potential use cases including as a tool for mix design, pavement monitoring, and pavement forensics.