Voltage Divider Calculator
Calculate output voltage from a two-resistor voltage divider.
Output voltage Vout (V)
2.5 V
Usage examples
Scaling a sensor signal down to a safe voltage
Calculate the resistor ratio needed to bring a high-voltage sensor output down to a level a microcontroller can safely read.
Creating a reference voltage
Find the resistor values needed to produce a specific reference voltage (Vref) from a resistor ratio.
Picking a resistor for a target division ratio
Set a target output voltage, then work backward to find the R1 or R2 value needed to achieve it.
Frequently asked questions
Is what I enter sent to a server?
No. All calculations happen entirely in your browser and are never sent to a server.
Where exactly are R1 and R2 positioned?
R1 sits between the input voltage and the output node; R2 sits between the output node and ground.
Does the result change if a load is connected?
Yes. This calculator assumes nothing is connected to the output (no load). If a low-impedance load is attached, the real voltage will be lower than the calculated value.
Can I type resistor values with kΩ or MΩ units?
Enter the number directly in ohms (Ω). For 10 kΩ, type 10000.