In this paper a coarse graining process is used to subsequently model large wildland fires, starting from a model of a single tree. The models are created using Wildland Urban Interface Fire dynamics Simulator (WFDS), and it is here found that reasonable fire spread in small forests can be obtained although the results are quite dependent on grid resolution as well as moisture content. In most realistic scenarios the computational volume is rather large yielding massive amounts of data. In using WFDS a rather small grid size is needed to appropriately model the fire spread this will be a severely limiting factor in creating large models.