Loaded Resistor Voltage Divider Calculator

Method, example, and limits

Formula: R₂,eff = R₂ ∥ Rᴸ; Vout = Vs·R₂,eff/(R₁ + R₂,eff). Currents and power follow Ohm's law and P = V²/R.

Inputs and units: Vs is the ideal source voltage, R₁ the upper series resistance, R₂ the lower resistance, and Rᴸ the load placed in parallel with R₂.

Worked example: With 12 V, R₁ = R₂ = 10 kΩ, and Rᴸ = 10 kΩ, R₂,eff = 5 kΩ and Vout = 4 V; source current is 0.8 mA.

Result meaning: The reported output is the loaded-node voltage; finite load resistance pulls it below the unloaded divider's 6 V result.

Assumptions: Steady-state ideal DC source and ideal resistors; all resistances are positive. Component tolerance, temperature, wiring, source impedance, and transient effects are excluded.

Limits: This is an ideal circuit calculation, not installation advice or a component rating recommendation. It does not assess isolation, fault conditions, thermal limits, or regulatory requirements.