Voltage Divider Calculator
Instantly calculate the output voltage of any resistor voltage divider. Useful for level-shifting 5V signals to 3.3V for ESP32/ESP8266 inputs, biasing op-amps, and ADC reference networks.
What is a voltage divider?
A voltage divider uses two resistors to reduce a voltage to a lower level. Common applications: monitoring battery voltage, reading analog sensors, level-shifting between different voltage domains, and biasing AC signals. The output voltage is always lower than input and depends on the resistor ratio, not the absolute values.
Simulated — dashes show current flowing from Vin to GND through R1 and R2. Vout tap draws no current (ideal, unloaded output).
Connected between Vin and Vout
Connected between Vout and GND
Output Voltage
2.500 V
- Voltage ratio
- 50.0%
- Current draw
- 0.250 mA
- R1 + R2
- 20.00 kΩ
Formula: Vout = Vin × R2 / (R1 + R2)
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