The Fulcrum Position calculator Lever with beam (x+y) and fulcrum. Where L = x + y computes the distance (x) from the object to the fulcrum based on the length of the beam (L), the mass of the object (W) and the downward force (F).. INSTRUCTIONS: Choose your preferred units and enter the following: (F) The downward force (weight) opposite the fulcrum from the object.