Voltage Divider Calculator

Enter an input voltage and two resistors, with an optional load resistance, to inspect a low-voltage resistor divider.

Input voltage

R1 (Ω)

R2 (Ω)

Load (Ω, blank = none)

—Output voltage across R2 / load.

—Vout / Vin

—Divider current

—Effective lower R

—Unloaded source R

A connected load changes the lower-leg resistance. For an unloaded divider, leave Load blank.

Educational / low-voltage electronics calculator. Real components have tolerances and non-ideal behavior. Do not use this page as a substitute for qualified design or safety guidance for mains/high-energy electrical systems.

How to use this Voltage Divider Calculator

Calculate unloaded or loaded resistor-divider output voltage, current, ratio, and power. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.