Voltage Divider Calculator

Find Vout, R1, or R2 for a resistive voltage divider.

Input voltage (V)

R1 (Ω)

R2 (Ω)

Output voltage (Vout) —

Division ratio —

Current through divider —

Vout = Vin × R2 / (R1 + R2). The output is taken across R2 (the bottom resistor).

🛒 Shop related: Electronics kits · Soldering gear · Arduino
Affiliate links — we may earn a commission at no cost to you. Learn more

Get your results + weekly electronics tips

One email per week. Tips, tool deals, new calculators. Unsubscribe anytime.

Free tools, useful tips. We recommend products we'd actually use.

How Voltage Dividers Work

A voltage divider uses two resistors in series to produce an output voltage that is a fraction of the input voltage. The formula is Vout = Vin × R2 / (R1 + R2).

Voltage dividers are used in sensor circuits, ADC reference inputs, level shifters, and biasing circuits. They work best when the load impedance is much higher than R2.

For a 50/50 split, use equal resistors. For a 1/3 split, use R1 = 2 × R2. Common values range from 1kΩ to 100kΩ depending on power constraints.