Voltage Divider Calculator
Calculate output voltage and current for a resistive voltage divider.
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A voltage divider uses two resistors in series to produce a lower output voltage from a higher input. It is one of the most common circuits in electronics - used for sensor interfacing, reference voltages and level shifting. This calculator gives you the output voltage, current draw and power dissipated.
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Frequently asked questions
Use R1 = 14 kΩ and R2 = 10 kΩ. The output is 12 × 10000 / (14000 + 10000) = 5V. The divider ratio is 0.4167.
A load in parallel with R2 reduces the effective bottom resistance, lowering the output. For stable outputs, keep the load resistance at least 10x higher than R2.
Vout = Vin × R2 / (R1 + R2). With equal resistors, the output is exactly half the input voltage.
Current through the divider is I = Vin / (R1 + R2). A 12V divider with 10 kΩ total resistance draws 1.2 mA continuously, wasting 14.4 mW.
Not recommended for power. Voltage dividers cannot supply significant current without voltage drop. Use a voltage regulator instead - dividers are best for signal level shifting and voltage sensing.