The following dataset comprises Saharan dust grain-size distributions from samples collected in submarine sediment traps in the eastern tropical North Atlantic Ocean during 2017 and 2018. The mooring was located at 12°N, 23°W and was deployed during the FORAMFLUX cruise in 2017 (doi: 10.2312/cr_m140) and recovered during the MACPEI cruise (doi: 10.2312/cr_msm79). Three funnel-shaped KUM sediment traps approximately 100m apart at depths 1074m, 1165m, and 1275m are referred to as traps U (upper), M (middle), and L (lower), respectively. The traps sampled at different time periods in order to span the collection period; L from August 2017-January 2018, M from February-June 2018, and U from July-November 2018. The traps were equipped with rotating carrousels each carrying 39 bottles in which the collected material was kept. The dataset features unprecedented resolution with each sample collected over 4-day periods, thus enabling the identification of individual dust outbreaks. Continuous sampling allowed for the observation of seasonal variations in grain-size distributions. Grain-size measurements were conducted using a Beckman Coulter Laser Diffraction Particle Size Analyzer LS13320 (LDA) at the Royal Netherlands Institute for Sea Research. The micro liquid module (MLM) was employed to detect fine grains ranging from 0.400 µm to 2.0 µm. The resulting grain-size distributions are provided as volume percentage versus 90 size bins. The LS13320 software supplies the metadata for the analysis, including the statistical parameters detailed in the dataset.