Accurate quantification of liver iron concentration (LIC) is needed for the assessment of iron overload. Quantification of magnetic susceptibility may enable accurate and reproducible estimation of LIC. SQUID-based biomagnetic liver susceptometry (BLS) is used clinically to measure magnetic susceptibility, but has very limited availability. MRI-based Quantitative Susceptibility Mapping (QSM) may enable liver susceptometry with much broader availability. However, the accuracy of QSM-BLS across field strengths remains unknown. In this abstract, we observed strong correlation (r2=0.90) between QSM-BLS (at both 1.5T and 3.0T) with SQUID-BLS in patients with known or suspected iron overload.