Voltage Divider Calculator
Get the output voltage from the input voltage and two resistors, and find the E24 standard resistor pair closest to the output you need.
With a load connected
Formula and cautions
Vout = Vin × R2 / (R1 + R2). A load on the output sits in parallel with R2 and pulls the voltage down. Keep the load resistance at least ten times R2. Dividers suit inputs that draw almost no current, such as a microcontroller ADC pin.
Frequently asked questions
Which resistors drop 5 V to 3.3 V?
R1 = 10 kΩ and R2 = 20 kΩ give about 3.33 V, and both are E24 standard values. Enter your target voltage above to see other pairs.
Can I power a motor or LED from a voltage divider?
It is not recommended. The output voltage sags as soon as load current flows, and the resistors waste power. Use a voltage regulator for power, and keep dividers for inputs that draw almost no current, such as an ADC pin.