What is the formula for a potentiometer voltage divider?

With no load, output voltage equals supply voltage times the wiper position as a fraction of total resistance: Vout = Vin x (R2 / Rtotal), where R2 is the resistance between the wiper and the bottom terminal.

Why does adding a load resistor change the output voltage?

A load resistor connected to the wiper sits in parallel with R2, lowering its effective resistance. This pulls the output voltage below the unloaded value, an effect known as loading error.

Does the direction of the wiper percentage matter?

This calculator treats 0% as the wiper fully at the bottom terminal (output near 0 V) and 100% as fully at the top terminal (output near the supply voltage). Physically reversing the pot's wiring flips this direction.

How much current flows through the potentiometer?

With no load, current equals the supply voltage divided by the total resistance and is the same through both halves. Adding a load resistor increases current draw from the supply and creates unequal currents in the two branches.

What is a good total resistance for a voltage divider pot?

Lower resistance pots (1 k-10 k) resist loading effects better but draw more current and dissipate more power. Higher resistance pots (100 k+) draw less current but are more sensitive to loading from whatever they connect to.

Potentiometer Divider Calculator

Name: Potentiometer Divider Calculator
Availability: InStock
Author: Nham Vu

Enter supply voltage, potentiometer resistance, and wiper position to get the divider output voltage, with an optional load resistor.

Divider Inputs

Supply Voltage (V)

Potentiometer Total Resistance

Wiper Position 50.0%

0% = wiper at bottom terminal, 100% = wiper at top terminal.

Load Resistance (optional)

Resistor from the wiper to the bottom terminal, e.g. an input impedance.

Result

Output Voltage

0.000 V

Loading Error

0.0%

R1 (top to wiper)

0 ohm

R2 (wiper to bottom)

0 ohm

Supply Current

0 mA

Power Dissipated

0 mW

Summary

Enter supply voltage, potentiometer resistance, and wiper position to get the divider output voltage, with an optional load resistor.

How it works

Enter the supply voltage applied across the two outer terminals of the potentiometer.
Enter the potentiometer's total resistance and pick the unit (ohms, kilohms, or megohms).
Set the wiper position as a percentage, from 0% (bottom terminal) to 100% (top terminal).
Optionally enter a load resistance connected from the wiper to the bottom terminal.
The tool computes the two sub-resistances at the wiper and the resulting output voltage.

Use cases

Set a trimmer potentiometer to a target reference voltage for a circuit.
Check how much a load resistor pulls down the output of a volume or level pot.
Design a voltage divider for a sensor bias or calibration input.
Verify wiper position math before building a physical prototype.
Teach how a three-terminal potentiometer behaves as a divider versus a rheostat.
Estimate current draw through a pot at a given supply voltage.

Frequently Asked Questions

Last updated: 2026-07-24 · Reviewed by Nham Vu