Voltage Divider Calculator
Estimate the output of a two-resistor DC voltage divider and account for an optional load across the lower resistor.
Enter circuit values
Divider output
About this calculator
Estimate the output of a two-resistor DC voltage divider and account for an optional load across the lower resistor. Use measured or manufacturer-specified values where available.
A load connected across the lower resistor reduces the effective resistance and can lower output voltage. The result also shows divider current and resistor power.
Method and assumptions
Without a load, output voltage is input voltage × R2 ÷ (R1 + R2). With a load, the lower leg is R2 in parallel with the load resistance; output voltage is then the input voltage multiplied by that effective resistance divided by R1 plus the effective resistance.
The model assumes ideal resistors with constant resistance at steady state. It excludes component tolerance, temperature rise, wiring resistance, reactive components, transients, and protective-device selection.
FAQs
Can I use this for AC circuits?
No. This calculator models ideal, steady-state DC resistors. It does not model reactance, phase angle, harmonics, or AC load behavior.
Does the result check component ratings?
No. Compare calculated voltage, current, and power with component datasheets and application limits before selecting or operating equipment.
Sources
Ideal resistor relationships from Ohm’s law and the DC power equation.