How to Calculate Vout in a Voltage Divider

A voltage divider is a simple circuit used to generate a lower voltage from a higher voltage. It consists of two resistors in series. The output voltage (Vout) is determined by the resistor values and the input voltage (Vin).

Voltage Divider Formula

The output voltage (Vout) is given by the formula:

Vout = Vin × (R2 / (R1 + R2))

Explanation

• Vin: The input voltage applied to the circuit.
• R1: The resistor connected between Vin and Vout.
• R2: The resistor connected between Vout and ground.

Example Calculation

Suppose we have:

• Vin = 12V
• R1 = 10kΩ
• R2 = 5kΩ

Using the formula:

Vout = 12 × (5k / (10k + 5k)) = 12 × (5 / 15) = 12 × 0.333 = 4V

So, the output voltage (Vout) is 4V.

Calculating R1 and R2

If you want to determine the resistor values for a desired Vout, you can rearrange the voltage divider formula:

To calculate R1:

R1 = R2 × ((Vin / Vout) - 1)

To calculate R2:

R2 = R1 / ((Vin / Vout) - 1)

Choose a suitable resistor value for either R1 or R2 and use these formulas to find the other.

Applications

Voltage dividers are commonly used in:

• Sensor interfacing
• Adjustable power supplies
• Signal conditioning

By choosing appropriate resistor values, you can achieve the desired output voltage for your circuit.