In 2015, 17 Sustainable Development Goals (SDG’s) were approved, including SDG13, which addresses actions to increase carbon capture (CO2-C storage) for climate change mitigation. However, no analytical procedures have been defined for quantifying soil organic carbon (SOC) sequestration. Here we present a rapid tool for guiding farmers and for monitoring SOC sequestration in farmers’ fields. The tool consists of multi-constituent soil analyses (through Near Infra-Red Spectroscopy (NIRS)) and a SOC mineralization model. The tool provides forecasts of SOC sequestration over time. Soil analyses via NIRS have been calibrated and validated for farmers’ fields in the UK, other European countries, China, New Zealand, and Vietnam. This tool allows fast, quantitative, and action-driven monitoring of SOC sequestration in farmers’ fields, and therefore is an essential tool for monitoring progress of SDG13.