Meteoric <sup>10</sup>Be (<sup>10</sup>Be<sub>met</sub>) concentrations in soil profiles great potential as a geochronometer and a tracer of Earth surface processes, particularly in fine-grained soils lacking quartz that would preclude the use of <i>in situ</i>-produced <sup>10</sup>Be (<sup>10</sup>Be<sub>in situ</sub>). One prerequisite for using this technique for accurately calculating rates and dates is constraining the delivery, or flux, of <sup>10</sup>Be<sub>met</sub> to a site. However, few studies to date have quantified long-term (i.e. millennial) delivery rates. In this study, we compared existing concentrations of <sup>10</sup>Be<sub>in situ</sub> with new measurements of <sup>10</sup>Be<sub>met</sub> in soils sampled from the same depth profiles to calibrate a long-term <sup>10</sup>Be<sub>met</sub> delivery rate. We did so on the Pinedale and Bull Lake glacial moraines at Fremont Lake, Wyoming (USA) where age, grain sizes, weathering indices, and soil properties are known, as are erosion/denudation rates calculated from <sup>10</sup>Be<sub>in situ</sub>. After ensuring sufficient beryllium retention in each profile, solving for the delivery rate of <sup>10</sup>Be<sub>met</sub> via Monte Carlo simulations, and normalizing to Holocene-average paleomagnetic intensity, we calculate best-fit fluxes of 0.92 (+/− 0.08) × 10<sup>6</sup> and 0.71 (+0.09/−0.08) × 10<sup>6</sup> atoms cm<sup>−2</sup> y<sup>−1</sup> to the Pinedale and Bull Lake moraines, respectively, and compare these values to two widely-used <sup>10</sup>Be<sub>met</sub> delivery rate estimation methods. Accurately estimating <sup>10</sup>Be<sub>met</sub> flux using these methods requires careful consideration of spatial scale as well as temporally varying parameters (e.g. paleomagnetic field intensity) to ensure the most realistic estimates of <sup>10</sup>Be<sub>met</sub>-derived erosion rates in future studies.