How this calculator works
Vertical force equilibrium sets the sum of reactions equal to the applied load. Moment equilibrium about the left support sets the right reaction. Upward applied forces and uplift reactions may be negative. Distributed loads can be entered as equivalent point resultants only when their resultant location is known.
Formula
RB = sum(Fi xi)/L; RA = sum(Fi)-RB. Missing F1 = [RB L - sum(other Fi xi)]/x1; missing x1 = [RB L - sum(other Fi xi)]/F1.
Worked example
A 4 m beam carrying 2 kN at 1 m and 4 kN at 3 m has RB = (2x1+4x3)/4 = 3.5 kN and RA = 2.5 kN.
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Frequently asked questions
Does this include beam self-weight?
Only if you add its resultant force at the centre of gravity. Include every applicable load.
Can I analyse an overhang?
No. This page restricts load positions to the span between the two supports.
Does a reaction prove adequate support?
No. Bearing, anchorage and the supporting structure require separate checks.