The U.S. EPA and ORNL have developed an online calculator called the Radon Vapor Intrusion Screening Levels calculator (RVISL) to provide screening levels for radon isotopes in groundwater, soil gas and indoor air to assist with vapor intrusion risk assessments. The calculator estimates indoor air concentrations from user-entered soil gas or groundwater levels using default attenuation factors, and can calculate risk values. It provides a more accessible alternative to spreadsheets for evaluating radon vapor intrusion risks.