In extensive research of over 20,000 software development projects spanning 18 years, it is found that more projects are doomed from poor cost and schedule estimates then they ever are from technical, political, or development team problems. Yet, so few companies and individuals really understand that software estimating can be a science, not just an art. It really is possible to accurately and consistently estimate development costs and schedules, for a wide range of projects. Although there is a wide range of software cost estimating tools on the market to help with this process, the critical success factor is to understand the fundamental concepts of estimating and implement the concepts with nothing more than simple mathematics found in a spreadsheet.