This presentation examines the process of quantifying the true global warming potential (GWP) to accurately inform the true impacts of building material choices. Tools like the web based NRMCA Concrete Carbon Calculator help concrete producers, contractors and design teams to collaborate on setting carbon budgets on projects and compares baseline projects to proposed projects to exceed embodied carbon reduction goals. Step-by-step details will demonstrate how to use the tool to set a carbon budget and write a specification that allows for the lowest possible carbon footprint for the ready mixed concrete proposed for various projects.