This paper deals with the behaviour and shear capacity of concrete beams reinforced with glass-fibre-reinforced polymer (GFRP) reinforcing bars. Twelve large-scale beams with a shear span to effective depth of beam ratio of less than 2·5 were tested. The beams were divided into two groups each comprising three GFRP-reinforced beams and three control conventional steel-reinforced beams. Concrete grade and longitudinal reinforcement ratio were varied. A new semi-analytical formula for estimation of the shear capacity of GFRP concrete beams was proposed based on the fracture mechanics approach. The accuracy of the proposed formula was verified using test results of the authors and other researchers. As a characteristic resistance model according to Eurocode 0, it was also compared with existing formulae published in various codes, manuals, guidelines and other studies. The formula was proved to be valid and thus could be applied to predict the shear capacity of beams more accurately.