The effectiveness of Fiber Reinforced Polymer (FRP) jackets in confining concrete columns significantly depends on fiber orientation. Most design guidelines limit the deviation angle from the hoop direction to 5°, yet this limitation lacks sufficient experimental justification, particularly for small deviation angles (< 15°). Moreover, in practical applications, small deviation angles may accidentally occur due to workmanship errors or construction limitations, which further highlights the need for investigation. To address this gap, the present study experimentally investigates the influence of small fiber deviation angles on the performance of FRP-confined concrete cylinders. A total of 39 plain concrete (30.1 MPa) cylindrical specimens were cast, most confined using one or two layers of Carbon Fiber Reinforced Polymer (CFRP) wraps and tested with inclination angles ranging from 0° to 15°. Results show that increasing the fiber deviation angle from 0° (hoop direction) to 15° reduces the confined strength and ultimate axial strain by approximately 22% and 35%, respectively, for single-layer CFRP-confined specimens, with comparable reductions for two-layer specimens. These findings indicate that the commonly adopted 5° deviation angle limit may lead to about an 8% reduction in confined strength and strain. Furthermore, modification factors are proposed to improve the accuracy of existing confinement models. The results of this study provide engineers with valuable experimental evidence for assessing the confinement efficiency of FRP jackets with small fiber deviations and for refining design predictions in practical applications.

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