Voltage Divider Calculator
Calculate the output voltage, current and resistor power of a two resistor divider, including the loading effect of a connected load.
Runs on your device
Result
Results appear here as you type.
What it does
Vout = Vin × R2 / (R1 + R2) only holds with no load. Add the load resistance (for example an ADC input) to see how much the output sags.
How to use it
- Enter Vin, R1 and R2.
- Optionally enter the load resistance.
- Read Vout and power dissipation.
Example
The example fills in realistic values and runs the tool. Select Try an example above to see it.
When it helps
- Scaling 12 V down for a 3.3 V microcontroller pin.
- Biasing transistor stages.
- Sensor interfacing.
Questions
Can I power a device from a divider?
Usually not. The output changes with load current; use a regulator instead.
Which resistor is R2?
The one between the output and ground.
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