Voltage Divider Calculator
Calculate the output voltage of a resistive or capacitive voltage divider circuit. Enter the input voltage and component values to find the divided voltage. Perfect for electronics design, sensor circuits, and signal conditioning.
What Is a Voltage Divider?
A voltage divider is a simple circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). It consists of two series-connected components — usually resistors or capacitors — and is one of the most fundamental circuits in electronics.
Voltage dividers are widely used in sensor circuits, reference voltage generation, signal conditioning, and biasing active components. The divider ratio determines how much of the input voltage appears at the output.
How Does the Voltage Divider Calculator Work?
The calculator supports two types of dividers:
Resistive Divider:
Vout = Vin × R2 / (R1 + R2)
Capacitive Divider:
Vout = Vin × C1 / (C1 + C2)
(For AC signals, the impedance of the capacitors matters: Vout = Vin × ZC2 / (ZC1 + ZC2))
The calculator also features a "Find R2 / C2" mode that solves for the missing component value when you know the desired output voltage.
Why Use This Voltage Divider Calculator?
- Two Divider Types: Supports resistive and capacitive dividers.
- Solve for Component: Find the required R₂ or C₂ value for a target output voltage.
- Multiple Units: Choose from ohms, kilo-ohms, mega-ohms for resistance, and F, mF, µF, nF, pF for capacitance.
- Visual & Detailed: Circuit diagram, bar chart, and detailed breakdown.
- Free & Private: No registration, no data storage.
Applications of Voltage Dividers
- Sensor Interfacing: Scaling sensor outputs to ADC input ranges.
- Reference Voltage: Generating stable reference voltages for comparators and ADCs.
- Signal Attenuation: Reducing signal amplitude for measurement.
- Biasing: Setting bias voltages for transistors and op-amps.
- Level Shifting: Shifting signal levels between different voltage domains.
❓ Voltage Divider FAQ
What is a voltage divider?
A voltage divider is a circuit that produces an output voltage that is a fraction of the input voltage. It typically consists of two resistors or capacitors in series.
What is the voltage divider formula for resistors?
Vout = Vin × R2 / (R1 + R2), where R1 is the top resistor and R2 is the bottom resistor.
What is the voltage divider formula for capacitors?
For a capacitive divider, Vout = Vin × C1 / (C1 + C2). For AC signals, impedance must be considered.
How do I choose resistor values for a voltage divider?
Choose values that give the desired ratio while keeping current consumption and power dissipation in check. Use the "Find R2" mode to solve for a specific output voltage.
What is the loading effect in a voltage divider?
Loading effect occurs when the load connected to the output draws current, reducing the output voltage. Use a buffer amplifier or high-value resistors to minimize this effect.
What is the difference between a resistive and a capacitive voltage divider?
A resistive divider works for both DC and AC signals. A capacitive divider only works for AC signals (since capacitors block DC) and is frequency-dependent.
How does frequency affect a capacitive voltage divider?
In a capacitive divider, the impedance of each capacitor is inversely proportional to frequency (ZC = 1/(2πfC)). The voltage division depends on the ratio of impedances, which changes with frequency.
What is the Thevenin equivalent of a voltage divider?
The Thevenin equivalent is Vth = Vin × R2 / (R1 + R2) with Rth = R1 || R2.
Can a voltage divider be used as a power supply?
Voltage dividers are not suitable as power supplies for anything other than very low current loads. The output voltage drops when current is drawn. Use a voltage regulator for power supply applications.
How do I calculate the current through a voltage divider?
Current = Vin / (R1 + R2). This is the current flowing through both resistors in series.
What is the best resistor ratio for a voltage divider?
The best ratio depends on your application. Lower value resistors provide better stability but consume more power. Higher value resistors reduce power consumption but are more susceptible to loading effects.
Can I use a potentiometer as a voltage divider?
Yes, a potentiometer is essentially an adjustable voltage divider. The output voltage is determined by the position of the wiper.
What is the difference between a voltage divider and a voltage regulator?
A voltage divider provides a fraction of the input voltage but is not regulated — the output changes with load and input variations. A voltage regulator maintains a constant output voltage regardless of load and input changes.
How do I convert a voltage divider output to a specific ADC range?
Choose resistor values so that the divider output stays within the ADC's input voltage range (0 to Vref). The "Find R2" mode can help you find the right value for a target output voltage.
What is the impedance of a voltage divider?
The output impedance of a voltage divider is R1 || R2 (the parallel combination of both resistors). This determines how much the output voltage drops under load.
Why do voltage dividers use 1% or 5% tolerance resistors?
Resistor tolerance affects the accuracy of the output voltage. For precision applications, use 1% or better resistors. For general use, 5% is often sufficient.
Can a voltage divider be used with AC signals?
Yes, resistive dividers work with AC signals. Capacitive dividers also work with AC signals but are frequency-dependent. The calculator supports both types.