Rebar materials are one of the major construction materials in a construction process that generate main contribution of construction and demolition (C&D) wastage. Therefore, a monitoring and controlling process as a part of waste management  in design, procurement and construction phases is obligatory. This paper presents a model for a rate calculation of rebar waste in the construction phase based on realtime progress by blending output from Building Information Modelling (BIM) Quantity Takeoff Software in the form of the report of total volume steel reinforcement and that of current rebar volume based on the existing progress to monitor spreadsheet to perform the rate calculation of real time and exact rebar waste. Simulation and “What if” scenario were applied to this proposed calculation model. For a 40% progress of the suspended road structure project, the proposed calculation model partakes 4,02% rebar waste rate. This result validates that the model can produce rebar waste rate based on the exisiting project progress.