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Voltage Divider Calculator

Calculate the output voltage of a two-resistor voltage divider circuit.

Inputs

Saved Scenarios

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Output Voltage (V)

8.000

Spark says

How it's calculated

Formula

Vout=Vin×R2R1+R2V_{out} = V_{in} \times \dfrac{R_2}{R_1 + R_2}
V_{in}
— Input voltage
R_1, R_2
— The two divider resistors, in series

What is the Voltage Divider Calculator?

A voltage divider uses two resistors in series to produce an output voltage that's a fraction of the input voltage, taken from the junction between them.

How to use it

  1. 1 Enter the input voltage.
  2. 2 Enter the value of R1 (top resistor).
  3. 3 Enter the value of R2 (bottom resistor, across which output is measured).

Worked examples

12V in, R1=1kΩ, R2=2kΩ

Output voltage is 8V.

Try it

Limitations

  • •Assumes no current is drawn by whatever the output connects to — a real load will pull the output voltage down.

Frequently asked questions

Which resistor sets the output voltage?

The output is measured across R2 (the resistor closer to ground). Increasing R2 relative to R1 increases the output voltage.