Calculate output voltage and resistor values for voltage divider circuits. Includes current and power dissipation.
Vout = Vin × R2 / (R1 + R2)
A voltage divider uses two resistors in series to reduce voltage. It is one of the most fundamental circuits in electronics, used for sensor interfacing, biasing transistors, and level shifting.
Generally no. Voltage dividers are for signal-level applications. For power, use a linear or switching voltage regulator.
Keep total resistance (R1+R2) between 1K and 100K for most applications. Use standard resistor values (E12/E24 series).
Enter the input voltage and two resistor values (R1 and R2). The calculator shows the output voltage and current through the circuit.
Vout = Vin Γ R2 / (R1 + R2). Current = Vin / (R1 + R2). Power: P1 = IΒ² Γ R1, P2 = IΒ² Γ R2.
Vin = 12V, R1 = 10kΞ©, R2 = 5kΞ©: Vout = 12 Γ 5/(10+5) = 4V. Current = 12V / 15kΞ© = 0.8mA. Useful for converting 12V sensor to 3.3V Arduino input.
Voltage dividers are affected by load β add a buffer (op-amp voltage follower) for sensitive circuits. For power applications, use a voltage regulator instead. Choose resistor values 10Γ higher than load impedance.