Longitudinal tensile failure of composite systems is governed by a cluster of single fiber failures occurring at microscale lengths on the order of few microns to a few hundred microns. It is challenging to experimentally measure tensile strength of single carbon fibers at such microscale gage-lengths. Single fiber strength data at millimeter-scale is typically extrapolated using Weibull weakest link statistics to determine fiber strength at microscale, often resulting in an overprediction. In this study, a transverse loading experimental technique is investigated for inducing axial stress concentrations in single carbon fiber over microscale gage-lengths for microscale fiber tensile strength determination. Single fiber transverse loading finite element (FE) simulations and transverse loading experiments are conducted to study the magnitude and length of axial stress concentrations in the fiber-indenter contact region for different indenter geometries (radii) and starting angle configurations. The magnitude and the length of axial stress concentrations are determined from FE simulations at experimentally observed axial failure stresses in terms of a stress concentration factor (SCF) and effective gage-length (Leff). FE simulation and transverse loading experimental results showed negligible axial stress concentrations (SCF ~ 1.2) in the fiber for transverse loading with a 500 µm indenter radius at a starting angle of 0° and fiber failure occurred anywhere within the tested fiber length. Compared to this, transverse loading with a 50 µm indenter radius at a starting angle of 28° resulted in significant axial stress concentrations in the fiber-indenter contact region with a SCF of ~13.5. Fiber failure is observed to occur near the contact experimentally and scanning electron microscope (SEM) imaging of failure surfaces showed a smooth compressive failure on the inside of the fiber and a rough texture tensile failure on the outside of the fiber. Leff predicted from FE simulation for these experiments is approximately 37 µm and the average axial stress over that length is ~9.3 GPa which is significantly higher than uniaxial fiber tensile strength of 4.93 GPa.