AbstractThe stoichiometric carbon to phosphorus ratios (rC:P) in suspended particulate organic matter (POM) are generally inversely correlated with surface phosphate (PO₄) concentration. However, it is uncertain if previously suggested relationships between rC:P and PO₄ are appropriate for the vertical export flux of organic matter. Using a global steady‐state inverse ocean biogeochemistry model and annual‐mean observed tracers, we estimate optimal parameters for both linear and power law representations of rP:C (= 1/rC:P), and find rP:C = (0.0066 ± 0.0018) × [PO₄] + (0.0053 ± 0.0010) and rP:C = (0.0112 ± 0.0018) × [PO₄]^(0.36±0.07), respectively, where [PO₄] is in μM. Both parameterizations allow us to fit global tracer observations equally well, but the power law model implies an up to 50% larger uptake rC:P in oligotrophic gyres. For both formulations, the POM export rC:P from the euphotic zone is nearly equal to the uptake rC:P, while the dissolved organic matter export rC:P is up to two times larger than the uptake rC:P. Although weakly constrained, our model suggests that in eutrophic regions the vertical organic P fluxes are attenuated faster with depth than the organic C fluxes. By contrast, in oligotrophic regions there are no discernible differences between the organic P and C flux‐attenuation profiles. As a result, the large spatial range of rC:P spanning 50–200 at the base of the euphotic zone is diminished to 110–160 at 2000 m depth. In oligotrophic regions at 150–500 m depths, our estimated export rC:P values are significantly lower than those measured with sediment traps, implying a potentially large modulation of export rC:P by migrating zooplankton within the twilight zone.