Truss Method of Joints Calculator

About this calculator

The method of joints is the standard hand-calculation technique for solving statically determinate trusses in structural and civil engineering: at each pin joint, the truss members are treated as two-force members (axial tension or compression only), and equilibrium requires the sum of forces in both the horizontal and vertical directions to equal zero — ΣFx = 0 and ΣFy = 0. At a simple joint with one unknown member inclined at angle θ carrying a vertical applied load, the member force works out to load ÷ sin(θ), with its horizontal pull or push on the joint equal to that force times cos(θ).

Engineers walk through a truss joint by joint, starting where only two unknown member forces meet so the two equilibrium equations can be solved directly, then move to the next joint using the forces just found. This calculator reproduces that single-joint case — enter the applied vertical load and the member angle to get the axial member force and its horizontal component, the same numbers a bridge or roof-truss design check would start from.