Triaxial magnetometers are a critical tool used to determine how mass, momentum, and energy are coupled through near-Earth space by various geophysical phenomena. These magnetic field sensors can be deployed on spacecraft orbiting the Earth or other planetary bodies, on suborbital sounding rockets that rapidly traverse through active aurora, or at remote ground stations built to withstand adverse conditions. Increasingly, however, low-cost versions of these sensors are being deployed at universities, high schools, and urban backyards as educational, outreach, or citizen science opportunities. These sensors provide an opportunity for low-cost access to science, where such opportunities may otherwise be inaccessible or sparse. For effective and accurate use, these magnetometers must first be calibrated, a process which can be both costly and complex. A low-cost methodology for calibration would provide the community at large with greater opportunities to use magnetometers. This manuscript presents analysis of the error associated with a low-cost method of ground-based magnetometer calibration using scalar references at a variety of price points, enabling greater potential scientific return from low-cost sensors and applications. The following tests will show how this low-cost calibration can achieve similar performance levels of high-precision calibration facilities (i.e., <0.3% error in one case).