New estimates of soil organic carbon (SOC) stocks for Scottish soils by horizon have been developed using updated data within the SSKIB dataset and newly derived estimates of bulk density using a Random Forest (RF) approach based on a limited dataset containing measurements of bulk density and SOC concentrations along with categorical data. The dataset comprises estimated carbon densities (g/cm3) and soil horizon carbon stocks (kg/m2) for the minimum, mean and maximum carbon concentrations for soils delimeated on the National Soil Map of Scotland. The dataset (SSKIB_horizon_Cstocks.xlsx) can be linked to the National Soil Map of Scotland (Soil Survey of Scotland Staff, 1981) and a Land cover map to show the distribution of SOC stocks in Scotland or as input for modelling (see 'Guidance_on_use_of_soils_data' document embedded within the zipped shapefile of the 1:250,000 Soil Map (National Soil Map) Version 1.3/1.4 (Hutton_Soils_250K_v1.4) on the James Hutton website). The work was funded by the Rural & Environment Science & Analytical Services Division of the Scottish Government including the Underpinning National Capacity fund.