High-resolution seawater δ18O records, derived from coupled benthic foraminifera Mg/Ca and δ18O analyses, can be used to evaluate how global ice volume changed during the Mid-Pleistocene Transition (MPT, ~1250-600 ka ago). However, such seawater δ18O records are also influenced by regional hydrographic signals (i.e. salinity) and changes in deep ocean circulation across the MPT, making it difficult to isolate the timing and magnitude of the global ice volume change.Here we generated a new seawater δ18O from coupled Mg/Ca and δ18O analyses of benthic foraminifera Uvigerina spp. Ocean Drilling Program Site 1208 in the North Pacific.We use PSU Solver (Thirumalai et al., 2016) to propagate error on seawater δ18O for ODP Site 1208 and previously published benthic foraminifera Mg/Ca and δ18O records from North Atlantic DSDP Site 607 (Sosdian and Rosenthal, 2009; Ford et al., 2016; Cibicidoides wuellerstorfi, Oridorsalis umbonatus, and Uvigerina spp.) and South Pacific ODP 1123 (Elderfield et al., 2012; Uvigerina spp.).Using these three records we generated a seawater d18O stack over the Mid-Pleistocene Transition.