This study investigated the behavior of square concrete columns confined with carbon fiber-reinforced polymer (CFRP) sheets. 30 column specimens were tested including plain concrete, reinforced concrete, and CFRP-confined columns of different concrete grades (M20, M30, M40) and CFRP layer configurations (1-3 layers). Results showed that: 1) Load capacity increased up to two CFRP layers then decreased for three layers while ductility continuously increased up to three layers. 2) Toughness index increased with concrete grade and number of CFRP layers. 3) Stiffness increased for CFRP-confined columns compared to plain and reinforced concrete columns.