Enhancing soil organic carbon (SOC) storage is a climate mitigation goal, yet the magnitude and persistence of carbon gains following land-use change remain uncertain across soil textures and depths. We quantified the relative influence of land use, time since conversion, and texture on SOC accrual after conversion of cropland to grassland. The study investigated nine long-term paired grassland–cropland sites across Germany, spanning a texture gradient (4–85% sand) and a duration of 8–100 years since conversion from cropland. Adjacent grassland and cropland plots with shared land-use history were sampled at 10–20 and 45–60 cm depth to assess physical and chemical soil properties and identify the main controls on SOC differences. Across sites, SOC was consistently higher in grassland than in cropland, with the smallest differences in coarse-textured soils. In the topsoil, SOC increased approximately linearly with years under grassland, with no early saturation, whereas subsoil trends were more variable. Across sites, SOC accrual was equally co-limited by carbon inputs, estimated by soil quality rating and duration, and stabilization capacity, with median particle diameter (D50) serving as a proxy for mineral surface area. These findings revealed that carbon build-up after conversion from cropland to grassland can be projected when accounting for time since conversion, productivity proxies, and soil context. The results provide robust, multi-site, texture-specific evidence for the potential of grassland management to enhance soil carbon storage for climate mitigation and long-term resilience