Purpose: Sarcopenia describes a progressive loss of muscle mass and function. Despite sarcopenias correlation with peri-operative morbidity and long-term survival, the simplest and most effective sarcopenia measure has not been identified. Sarcopenia literature frequently reports psoas muscle area (PMA) indexed by height squared (PMA/H2 or PMI) (and less often body surface area (PMA/BSA)). The intention of indexing muscle area measures, is to reduce the impact of body size, improving the relationship between muscle area and surgical outcomes. Whilst indexing has been widely reported in the literature, its effectiveness has not been critically examined. Methodology: A retrospective cohort study included 432 patients who underwent elective colorectal surgical resection at University Hospital Geelong, with peri-operative morbidity and long-term survival to five years. PMA was measured from pre-operative CT scans, and height/weight from pre-operative notes to calculate PMI and PMA/BSA. Pearson correlations investigated the impact of indexing PMA. PMA, PMI and PMA/BSA were compared with peri-operative morbidity (by logistic regression) and long-term survival (Kaplan-Meier analysis). Results: Unindexed psoas muscle area correlated well with psoas muscle area indexed by height squared (R2=0.950) and by body surface area (R2=0.938). Long-term survival was associated with PMA (HR1.886 (95%CI 1.322-2.692)), but did not correlate significantly with PMI (HR1.451 (95%CI 0.969-2.172)), or PMA/BSA (HR1.292 (95%CI 0.859-1.942)). PMA, PMI and PMA/BSA did not correlate significantly with peri-operative morbidity in this study. Conclusion: Indexing sarcopenia measurements is commonly reported in the literature, however its effectiveness has not been critically examined. Indexing adds substantially to the time and effort required to measure PMA. In this study we report that indexing has a small numerical impact on PMA, and a detrimental effect on the relationship with long-term survival.