The majority of the roundwood processed by the highly concentrated forest products industry in Finland is supplied by non-industrial private forest owners (NIPF). The industry's heavy reliance on NIPF roundwood supplies and the NIPF owners’ high dependency on the industry for revenue motivated this study of the spatial fibre flows in regional markets. To describe the direction and magnitude of these regional fibre flows we estimate a mill-specific timber demand equation. This empirical model of roundwood demand can be used as a benchmark for identifying inefficiencies in wood procurement procedures. This study expands on the theoretical and empirical literature by increasing the spatial resolution of timber demand estimates.