Voltage Divider Calculator

Calculate output voltage, or find resistor values for a desired output.

Input Voltage (Vin)

R1 (top resistor)

R2 (bottom resistor)

Output Voltage (Vout)

2.500 V

Ratio: 50.0%

Current: 0.25 mA

Output impedance: 5.00 kΩ

Find Resistors for Target Voltage

Target Vout

From Vin

Preferred R2

kΩ

Required R1: 5.15 kΩ

Nearest E24: 5.1 kΩ → 3.31 V

Output voltage: $V_{out} = V_{in} \cdot \frac{R_2}{R_1 + R_2}$
Output impedance: $Z_{out} = R_1 \parallel R_2 = \frac{R_1 \cdot R_2}{R_1 + R_2}$

Loading effect: If your load resistance is less than ~10× $Z_{out}$, the output voltage will drop. Use lower resistor values or add a buffer.