Voltage Divider Calculator

A voltage divider uses two resistors in series to produce a fraction of the input voltage, a common circuit in electronics and sensors.

Find
Results update as you type.

Output voltage

3.83673 V

Ratio Vout ÷ Vin
0.319728
Current through the divider
816.33 µA
Power in R1 and R2
6.664 mW and 3.132 mW

This is the unloaded output. A load connected to Vout acts in parallel with R2 and pulls the voltage down unless it is much larger than R2.

About this calculator

Find the output, or the R2 that gives the voltage you need.

How to use it

  1. Choose what to find.
  2. Enter the input voltage and resistors.
  3. Read the output, current and power.

The formula

Vout = Vin × R2 ÷ (R1 + R2)
R1
top resistor, from Vin
R2
bottom resistor, to ground

Worked example

12 V with R1 = 10 kΩ and R2 = 4.7 kΩ

  1. Vout = 12 × 4.7 ÷ 14.7 = 3.84 V.

What the result means

Use larger resistors to waste less current, but keep them much smaller than any load connected to the output.

Assumptions

  • No load on the output.

Limitations

  • Not suitable for powering devices; use a regulator for that.

Frequently asked questions

What is a potential divider?

The same circuit: two resistors in series sharing the voltage.

Why does my output read low?

The load draws current and acts in parallel with R2.

Can I divide AC?

Yes, with resistors it works for AC too.

Last reviewed on 6 October 2026. Found a mistake? Tell us.