Calculate Potentiometer Divider Output by Wiper Position
Input Voltage Vin (V)
Total Resistance Rtot (Ω)
Taper Type
Wiper Position: 50%
0% (GND)100% (Vin)
Result
Output Voltage
Rwiper-gnd
Step-by-Step Calculation
Variable Divider Formula
Vout = Vin × R₂ / (R₁ + R₂)
R₂ = Rtot × position% (linear)
R₂ = Rtot × (10position%-1)/9 (log)
R₁ = Rtot - R₂
The variable resistor divider uses a potentiometer wiper to tap the resistive element at any point. The output voltage is proportional to the wiper position for linear taper. Log (audio) taper provides logarithmic response for volume control applications.
⚠The divider output is valid only when no significant current is drawn from the wiper (high-impedance load). Loading the output changes the effective divider ratio and voltage.
What is a Variable Resistor Divider?
A variable resistor divider uses a potentiometer (three-terminal device) with a movable wiper. The resistive element acts as two series resistors whose ratio changes with wiper position. This provides an adjustable output voltage from 0 to Vin, used in volume controls, brightness adjusters, and variable references.
Voltage Divider
Vout = Vin × R2/(R1+R2). R2 is wiper-to-ground. Vout ranges from 0 (0%) to Vin (100%).
Linear Taper
Resistance proportional to position. R2 = Rtot × pct. Vout is linear with knob angle. Used for adjustments.
Log Taper (Audio)
Exponential resistance curve. Matches human hearing perception. Used for volume controls and audio gain.
Loading Effect
If the load draws current, the divider output changes. Use a buffer (op-amp) for precise voltages. Rule: load resistance >> Rtot.
Volume ControlBrightness AdjustReference VoltageSensor CalibrationAudio Tone Control
Frequently Asked Questions
How does a variable resistor divider work?▼
A potentiometer wiper divides the resistor into two parts. Output Vout = Vin × R2/(R1+R2). Moving the wiper changes the ratio.
Linear vs log taper?▼
Linear: resistance changes evenly with angle. Log: exponential curve, used for audio volume (matches human hearing). Use "A" prefix for audio (A10k), "B" for linear (B10k).
What value potentiometer to use?▼
10kΩ is most common. Choose low values (1k-10k) for low-noise. High values (100k-1M) for low power consumption. Match to circuit impedance.
Does load affect divider output?▼
Yes! A load resistor from wiper to ground changes the effective R2. For accurate output, use a buffer (op-amp voltage follower). Rule: load ≥ 100× Rtot for minimal error.
Free online calculators and tools covering mathematics, unit conversion, text processing, and daily life. Accurate, fast, mobile-friendly, and completely free to use.