Efficient grazing management requires anticipation and flexibility and would be greatly facilitated by the development of dynamic tools with the capability to simulate different scenarios based on regular measurement of grass supply on the farm. Pastur’Plan, built on a spreadsheet within a partnership between INRA and a livestock management advisory association (Orne Conseil Elevage), combines two complementary concepts. The first is inspired by the Grass Wedge method adapted to French grazing conditions to highlight the distribution and coherence of grass supply on the paddocks on a farm and the requirements for grass based on the grazing rules and objectives. The second concept allows us to describe the evolution of the balance between grass growth and demand according to various grazing simulations on a paddock-by-paddock basis. This paper describes the hypothesis and calculations implemented, and subsequently the simulation method used and the illustrations dedicated to help support decisionmaking by grazing managers.