We compiled a database of bacterial abundance of 39 766 data points. After gridding with 1 spacing, the database covers 1.3% of the ocean surface. There is data covering all ocean basins and depth except the Southern Hemisphere below 350m or from April until June. The average bacterial biomass is 3.9±3.6 μg l−1 5 with a 20-fold decrease between the surface and the deep sea. We estimate a total ocean inventory of about 1.3×1029 bacteria. Using an average of published open ocean measurements for the conversion from abundance to carbon biomass of 9.1 fg cell−1, we calculate a bacterial carbon inventory of about 1.2 PgC. The main source of uncertainty in this inventory is 10 the conversion factor from abundance to biomass.