The authors investigated a novel functional pain scale, the Activity-Based Checks (ABCs) of Pain, following open urologic surgery. The primary objectives were to establish the strength of the correlation between the ABCs and the numeric rating scale (NRS) and determine the impact of functional pain on the patient's opioid requirements. We hypothesized that ABC score would correlate strongly with NRS and that the ABC score during hospitalization would be more closely correlated with the number of opioids prescribed and used. This prospective study included patients at a tertiary academic hospital undergoing nephrectomy and cystectomy. The NRS and ABCs were collected pre-operatively, during the inpatient stay, and at the one-week follow-up. Milligrams of morphine equivalents (MMEs) prescribed at discharge and the MME reportedly taken during the first post-operative week were recorded. Spearman's Rho was used to assess the correlation between scale variables. Fifty-seven patients were enrolled. The ABCs correlated strongly with the NRS at baseline and post-operative appointments (r = 0.716, p < 0.001 and 0.643, p < 0.001). Neither the NRS nor the composite ABCs score was predictive of outpatient MME requirements; the ABCs function, "Walking outside the room" significantly correlated to MMEs taken after discharge (r = 0.471, p = 0.011). The greatest predictor of MMEs taken was the number of MMEs prescribed (0.493, p = 0.001). This study highlighted the importance of post-operative pain assessment that takes functional pain into consideration to evaluate pain, inform management decisions, and reduce opiate reliance. It also emphasized the strong relationship between opioids prescribed and opioids consumed.