Thévenin / Norton Equivalent Calculator

Thévenin's and Norton's theorems say that any linear two-terminal network, however complicated inside, behaves at its terminals exactly like one source behind one resistance. Thévenin's form is a voltage source V_th in series with a resistance R_th; Norton's form is a current source I_N in parallel with the same resistance. Reducing a network to one of these makes it trivial to see what any load will do.

This calculator works the canonical textbook configuration so the reduction is exact and easy to follow: an ideal source V_s behind a series resistor R1, with a resistor R2 bridging the output terminals, feeding a load R_L. It finds the open-circuit terminal voltage V_th = V_s·R2/(R1+R2), the resistance R_th = R1∥R2 seen from the terminals with the source zeroed, and the short-circuit (Norton) current I_N = V_th/R_th. It then attaches your load to the equivalent and reports the load voltage, current, and power — and the maximum-power-transfer point, R_L = R_th, where the load draws the most power the network can deliver.

The scope is deliberately bounded: this is the two-resistor case, not a general network solver. That keeps every step visible — find the open-circuit voltage, deactivate the source and look back for the resistance, convert to Norton — which is exactly the procedure you apply by hand to bigger networks. Use it to learn the method, to reduce a divider-with-source that feeds a load, and to reason about loading and power transfer; for arbitrary multi-loop networks, reduce them to this form first or use nodal/mesh analysis.