This tool calculates the voltage drop across each resistor in a series network of two resistors.

Enter

- Input Voltage
**Vin** **R1**and**R2**in milliOhm/Ohm/kiloOhm/megaOhm

**Formula**

Ohm’s law is used to calculate the voltage drops. The current through each series resistor is the same as the total current through the circuit.

Therefore the total current **I _{total} **is given by

**I _{total} = Vin/(R1+R2) = V1/R1**

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

**I _{total} = Vin/(R1+R2) = V2/R2**

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

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

If you want to calculate the voltage drop across a single resistor set R2=0 and from the equations above, V1=Vin and V2=0 (which makes sense).

**Example Calculation**

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

- V1=3V
- V2=9V

The sum of the two voltages = the input voltage. As a check you can see that 3+9= 12V

**Related Calculators**

Voltage Divider Calculator with 3 resistors

Voltage Divider Calculator with 4 resistors

Voltage Divider Calculator with 5 resistors