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Voltage Divider Calculator

Calculate the output voltage of a two-resistor divider circuit instantly.

Circuit Values

V

Schematic & Output

5V
10 kΩ
2.50 V
10 kΩ
Output Voltage (Vout) 2.50 V

About Voltage Dividers

What is a Voltage Divider?

A voltage divider is a simple passive linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). It is one of the most fundamental circuits in electronics, commonly used to step down voltages to safe levels for microcontrollers (like reading a 5V sensor on a 3.3V Arduino or ESP32 pin), or to establish reference voltages.

The Formula

The output voltage is determined by the ratio of the two resistors. The mathematical formula is:

Vout = Vin × (R2 / (R1 + R2))

Important Design Considerations

  • Do not use for power supplies: Voltage dividers are meant for signals and references, not for drawing power. If you connect a load (like a motor or an LED) to Vout, the resistance of the load alters the circuit, causing the voltage to drop significantly.
  • Impedance: For reading sensors with an ADC (Analog-to-Digital Converter), try to keep the total resistance of the divider relatively low (typically under 10kΩ) so the ADC capacitor can charge fast enough, unless you are buffering it with an op-amp.