This study conducted compression tests to assess the behavior of ultra-high-performance concrete (UHPC) subjected to uniaxial compression. The primary test parameter is the fiber volume fraction in the 0 % to 2 % range. According to the test results, the presence of steel fibers in the matrix significantly affected the failure mode of UHPC. However, the compressive behavior of the test specimens appeared to be very similar, regardless of the fiber volume fraction. The compressive strength of UHPC was improved by approximately 10 % by the addition of the steel fibers. However, the fiber volume fraction and transverse strain had a strong association. The steel fibers significantly affected the volume change of the UHPC. Based on the test results and numerous test data sets, this study suggests that the compressive strength of the UHPC with steel fibers is a function of the UHPC compressive strength without steel fibers and design compressive strength. In addition, the elastic modulus for design is suggested. The proposed equations are applicable for the design and analysis of the UHPC with a fiber volume fraction of up to 6 % and a compressive strength between 120 and 255.9 MPa.