About this voltage divider calculator
Calculate the output voltage of a two-resistor voltage divider, or find the resistor value needed for a target output. The current through the divider and the power dissipated in each resistor are shown too.
How to use the Voltage Divider Calculator
- Enter the input voltage and resistor values.
- Read Vout, current and power.
- Or enter a target Vout to solve for R2.
Example
Vin 12 V, R1 10 kΩ, R2 4.7 kΩ → Vout ≈ 3.84 V
Frequently asked questions
What is the voltage divider formula?
Vout = Vin × R2 / (R1 + R2).
Can I power a device from a voltage divider?
Generally no. The load changes the output voltage; use a regulator to power circuits and dividers for signals or reference levels.
Is my data safe?
Yes. The tool runs entirely in your browser using WebAssembly. Nothing you type or upload is sent to a server, logged or stored.
Is it free?
Yes, completely free with no sign-up, no limits and no watermarks. It also works offline once the page has loaded.