The accurate cost estimate is one of the success keys to construction projects. The influence of inaccurate
cost estimation on construction projects is critical. There is no consensus among researchers about the
most important factors influencing the cost estimate accuracy. The study’s objective is to get an accurate
cost estimate because the precise cost estimate keeps all parties focused on delivering the project within
the budget. This objective is achieved by collecting the influential factors from the literature review and
creating a powerful arithmetical model of cost estimation. Twenty-nine factors were collected by reviewing
many researches. A questionnaire was prepared and then was examined by fourteen project managers.
Pareto technique was conducted to get the foremost influential factors. Based on the Pareto
technique, the 29 factors were reduced to nine. Then, a powerful arithmetical model was created in this
study to get an accurate cost estimate. Finally, fourteen finished projects were selected to be case studies.
The cost variance percentages were between 1% and 15% for each case study. By using the model,
the estimated contract value of each case study was recalculated and, the cost variance percentages
were between 0.5% and 0.8% for each case study.