Leveraging aerosol data from multiple airborne and surface-based field campaigns encompassing diverse environmental conditions, we identify a generally consistent oxalate-sulfate mass ratio, with a median of 0.0217 (95% confidence interval: 0.0154 – 0.0296; r = 0.76). Ground-based aerosol data show that the median oxalate-sulfate ratio is robust within both the mixed layer and the submicrometer particle size range, with higher values observed for supermicrometer particles. We demonstrate that dust and biomass burning emissions can separately bias this ratio towards higher values by at least one order of magnitude. Since sulfate is more readily measured, this ratio could be used to infer oxalate from sulfate in the absence of biomass burning and/or air masses rich with coarse aerosol types (especially dust). This ratio may also have implications for model estimates of secondary organic aerosol (SOA) formation, and particularly the aqueous processing route for oxalate production.