In recent years, the impact of the construction industry on the economy of India is increasing. However, there are a number of problems that are being faced by the construction companies or contractors or other relevant stakeholders, in the completion of a construction project. One of the major problems being faced is time and cost overrun. Thus, it is important to find ways of mitigating this critical problem. One of the solutions that is being used is the prediction of the amount and time that a project might overrun beforehand i.e. estimating the overrun during the design phase itself. This prediction can be done using a number of different techniques, the important one of which used in this paper is through the use of Fuzzy Logic. It also provides a brief description about the factors that are responsible for causing this cost overrun. The factors are identified by conducting a questionnaire survey and gathering responses from the relevant stakeholders which include contractors, project engineers, architects and consultants. The responses collected are further processed and analysed using SPSS software. The top 5 factors have been selected after the analysis and further used in preparation of the fuzzy logic model in the fuzzy toolbox of MATLAB. Further, the validation of this model has been done with real-time data of projects from various published research papers. Thus, the model developed provided prediction of the percentage of the cost overrun based on the percentage input of the top five factors.