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Voltage Divider Calculator

Calculate voltage divider values quickly and easily.

STEP 1

What do you want to calculate?

Output Voltage Calculate Vout
Input Voltage Calculate Vin
R1 Calculate upper resistor
R2 Calculate lower resistor
Result

What is a Voltage Divider?

A voltage divider uses two resistors to produce a lower voltage from a higher input voltage.

Vout = Vin × R2 ÷ (R1 + R2)

Voltage Divider Circuit

The basic circuit has R1 connected between the input voltage and output, while R2 connects the output to ground.

Vin → R1 → Vout → R2 → GND

Formulas

Output Voltage

Vout = Vin × R2 ÷ (R1 + R2)

Input Voltage

Vin = Vout × (R1 + R2) ÷ R2

R1

R1 = R2 × (Vin ÷ Vout - 1)

R2

R2 = R1 × Vout ÷ (Vin - Vout)

Example

Suppose you have:

  • Vin = 12 V
  • R1 = 10 kΩ
  • R2 = 10 kΩ
Vout = 12 × 10000 ÷ (10000 + 10000)

Vout = 6 V

Common Applications

  • ADC voltage measurement
  • Microcontroller circuits
  • Sensor circuits
  • Analog circuits
  • Reference voltage circuits