Looking into the research of the last 20 years, opening up the R&D process seems to help companies to be more successful. Looking for external ideas, based on market demands or external solutions to internal technical problems, helps to save time, reduce costs or find entirely new solutions. Having said that, opening up the R&D process also bears risks. If a company is willing to open up their R&D process, to what point should the process be opened? In a quantitative study with 100 German companies, followed by a qualitative study conducting interviews at 20 companies, an approach how to define this optimal point of openness was developed. First, the value of the real openness (RO) was measured directly; then the value for the virtual openness (VO) was calculated looking at risks and opportunities. Finally using the difference between the values of the RO and ideal opening (IO), recommendations to open the R&D process to an ideal level, the IO, can be derived.