Fractional flow reserve derived from coronary computed tomography enables anatomical and haemodynamic assessment of coronary artery disease in a single non-invasive test. Its diagnostic performance has been established against invasive fractional flow reserve in multi-centre trials, and a growing body of evidence has demonstrated its utility in predicting clinical outcomes. The purpose of this article is to describe the physiological principles, review its diagnostic performance, and describe the role of this technology in a real world clinical application.