In this paper, we investigate the extent to which well-known sediment transport capacity formulas can be used in one-dimensional (1-D) numerical modelling of dam-break waves over movable beds. The 1-D model considered here is a one-layer model based on the shallow water equations, a bed update (Exner) equation, a space-lag equation for the non-equilibrium sediment transport and an empirical formula calculating the sediment transport capacity of the flow. The model incorporates a variety of sediment transport capacity formulas proposed by Meyer-Peter and Müller (1948), Bagnold (1966), Engelund and Hansen (1967), Ackers and White (1973), Smart and Jaeggi (1983), van Rijn (1984a,b), Rickenmann (1991,2001), Cheng (2002), Abrahams (2003) and Camenen and Larson (2005). We examine the performance of each formula by simulating four idealized laboratory cases on dam-break waves over sandy beds. Comparisons between numerical results and measurements show that for each case better predictions are obtained using a particular formula, but overall, formulas proposed by Meyer-Peter and Müller (1948) (with the factor 8 being replaced by 12), Smart and Jaeggi (1983), Cheng (2002), Abrahams (2003) and Camenen and Larson (2005) rank as the best predictors for the entire range of conditions studied here. Moreover, results show that in the cases where a bed step exists, implementing a mass failure mechanism in the numerical modelling plays an important role in reproducing the bed and water profiles.