Voltage Divider Calculator

Calculate the output voltage of a voltage divider circuit by entering the supply voltage and resistor values below.

Output Voltage Results:

  volts


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How to Calculate Output Voltage for a Divider Circuit

A voltage divider circuit is a very common circuit used in electronics, and consists of two resistors connected to step down the supply voltage in the circuit. The ratio of the two resistors used determines the amount that the voltage is reduced.

The amount the supply voltage is scaled down is determined by the ratio of the resistor values to each other. That ratio can be expressed as the second resistance divided by the sum of the two resistances, or the ratio of the second resistance to the total resistance.

voltage divider circuit with two resistors
Diagram showing a voltage divider circuit with two resistors.

Voltage Divider Output Formula

Using the ratio above, the formula to calculate the output voltage of the divider can be expressed.

Vout = Vin × R2R1 + R2

Thus, the output voltage is equal to the input voltage times the resistance ratio which is expressed as the second resistance divided by the sum of the resistance in the divider circuit.

For example, let’s find the output voltage of a divider circuit with a 12 V supply voltage using 4.7 kΩ and 3.9 kΩ resistors.

Vout = 12 V × 3,900 Ω4,700 Ω + 3,900 Ω
Vout = 12 V × 0.4535 Ω
Vout = 5.4419 V