Voltage Divider Calculator 3 Resistors (with Examples)

This tool calculates the voltage across each of three (3) resistors in series.

Enter the Input Voltage Vin, and resistor values R1, R2, and R3.

Formula

V1=Vin*R1/(R1+R2+R3)

V2=Vin*R2/(R1+R2+R3)

V3=Vin*R3/(R1+R2+R3)

The largest voltage drop will be across the largest resistor value. Conversely, the smallest voltage drop will be across the smallest.

If you want to calculate the voltage drop across two resistors in series, set R3=0. In the equations above V3 will be zero (no voltage drop across a short circuit) and effectively this is reduced to a two resistor divider network.

Example Calculation

With R1=1Ω, R2=3Ω, R3=5Ω and Vin=12V, the voltages

  • V1 = 1.33V
  • V2 = 4V
  • V3 = 6.67V

The sum of the 3 voltages = the input voltage. As a check you can see that 1.33+4+6.67 = 12V

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