This paper presents a model for estimating the conceptual cost of reinforced concrete buildings in Qatar. The model relates building cost to building area using a parameter cost (σ) and uses a cost capacity factor (X) in an exponential model to estimate the cost of new buildings based on known building costs and areas. Values of σ and X were derived from historical building cost and area data. σ was found to decrease from 1981 to 1686 Qatari Riyals from 2002 to 2012, reflecting increasing competition among contractors. X values ranged from 0.379 to 0.856 from 2002 to 2012. Estimates using the model closely matched actual costs, validating the approach for cost estimation in Qatar.