An experiment was conducted to determine the energy release of a commercial phytase fed to broilers at multiple doses in basal diets that varied in ME. Dietary treatments included 3 negative controls ( NC ; 0.75% calcium and 0.30% non-phytate phosphorus) formulated at 3 ME levels (2,701, 2,868, and 3,000 kcal/kg). A commercial phytase product was added to each NC diet at 1,500, 4,500, 13,500, and 30,000 FTU/kg, creating a total of 15 dietary treatments. The phytase utilized was a phytase sourced from an Escherichia coli species bacterium expressed in a Trichoderma reesei fungus. Treatments were arranged in a 5 (phytase dose) × 3 (ME level) factorial in a randomized complete block design with 9 replications of 10 male broilers fed each of 15 dietary treatments for 21 d. On d 7, 14, and 21, birds provided the 3,000 kcal/kg diet had the lowest bird FI, and birds provided the 2,701 and 2,868 kcal/kg diets had the highest ( P < 0.001). Additionally, FCR decreased as ME increased ( P < 0.0001). Trends were observed for ME level × phytase dose interactions for d14 and 21 FCR. These trends demonstrate that phytase was most beneficial with the low energy diets. Eight treatments were selected for apparent ileal digestible energy ( AIDE ) analysis based on d 14 and 21 FCR data; AIDE ranged from 2,816 to 3,485 kcal/kg. Contrary to past studies, clear results were not observed for the energy releasing efficacy of graded levels of phytase. Performance improvements with phytase supplementation were likely more associated with P availability than AIDE.