The study looked at how bank capital and efficiency affect the performance of Nigerian banks. They used data from 15 banks between 2012 and 2015. The standard capital ratio of equity-to-total-assets was found to be the best measure for bank performance. Both risk-based and non-risk-based capitals had positive effects on bank performance, but only equity-to-total-assets influenced all performance indicators positively. Operating efficiency, measured by cost-to-income ratio, had a negative impact on bank performance. The study suggests that banks should incorporate the standard capital ratio of equity-to-total assets into their regulatory regime to improve their performance.