R2-based techniques for liver iron quantification using Spin-Echo (SE) imaging require long acquisitions. In contrast, single-voxel Stimulated-Echo Acquisition Mode (STEAM)-MR spectroscopy enables liver R2 measurements in a single breath-hold. However, the accuracy and field strength dependence of STEAM-MRS R2 quantification are unknown. This study evaluated the accuracy and field strength dependence of STEAM-MRS for R2 quantification in healthy controls and patients with liver iron overload. At 1.5T, STEAM-MRS R2 was in close agreement with SE-MRI-based R2. Further, STEAM-MRS R2 measurements were highly correlated across field strengths. Finally, STEAM-MRS R2 measurements at 1.5T and 3.0T were calibrated to liver iron concentration.