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Potentiometer Output Voltage Calculator

Enter the input voltage and wiper position to get the potentiometer output voltage.

How it is calculated

The tool treats the potentiometer as a two-resistor voltage divider with nothing connected to the wiper:

Vout = Vin × p / 100

where Vin is the voltage across the two end terminals in volts, and p is the wiper position in percent of full travel, 0 at the ground end and 100 at the supply end. The track's total resistance cancels out, so a 10 kΩ and a 100 kΩ pot give the same unloaded voltage. A position below 0 or above 100 returns no result. The answer is rounded to two decimals and shown in volts; a negative input voltage simply gives a negative output, because the formula is linear.

Worked example

A 12 V supply is connected across the pot, and the wiper is turned to 37.5% of its travel. Convert the position to a fraction: 37.5 / 100 = 0.375. Multiply by the input voltage: 12 × 0.375 = 4.5. The wiper voltage is 4.50 V. Turning the knob to 100% would give the full 12 V, and 0% would give 0 V.

Try this example →

Common mistakes

  • Entering the position as a fraction, such as 0.375, instead of a percentage. The field expects 0 to 100, so 0.375 is read as 0.375% and gives a tiny voltage.
  • Using the result for a loaded circuit. The formula assumes nothing draws current from the wiper; a load in parallel with the lower part of the track pulls the voltage down, and the lower the load resistance, the larger the error.
  • Confusing the rotation angle with the track position. On a logarithmic (audio) taper pot, 50% of the knob rotation is not 50% of the resistance, so convert the knob angle to the real track percentage first.
  • Typing the potentiometer's resistance and expecting it to matter. It is not an input, because it cancels out for an unloaded output.
  • Entering a position above 100, for example a raw ADC reading. The tool returns nothing outside 0 to 100.

About this calculator

A potentiometer wired as a voltage divider taps off a fraction of the input voltage at its wiper contact, proportional to how far along the resistive track the wiper sits. With an unloaded (high-impedance) output, the wiper voltage is simply Vout = Vin × (wiper position ⁄ full travel) — for example, a wiper at 30% of full travel outputs 30% of the input voltage, regardless of the potentiometer's total resistance.

This is the basic operating principle behind volume knobs, joystick position sensing, throttle position sensors, and analog control dials in electronics design. Engineers and hobbyists use this calculation to predict the output voltage at any wiper position before assuming a loaded circuit will behave the same way.

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Comments (1)

  • Editorial team

    This is the unloaded figure, so it holds only while whatever is connected to the wiper draws almost no current. A common rule of thumb is a load at least ten times the pot's track resistance; a lower load pulls the real voltage below what the tool shows. Also, the position is the fraction of resistance, which matches knob travel on a linear pot but not on an audio taper. What is your wiper feeding?

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