Voltage Divider
Divider values
Enter Vin, R1 (top) and R2 (bottom). Add R_L to see the loaded output.
Output voltage
How to use this calculator
A two-resistor voltage divider produces a fixed fraction of its input voltage: Vout = Vin · R2/(R1+R2), where R1 is the upper resistor and R2 the lower one (to ground). Enter Vin, R1 and R2; the unloaded output, the divider ratio and the current through the chain appear live. Optionally enter a load resistor R_L across the output to see the loaded value and how much the loading droops the voltage.
What it means in a real circuit
Dividers are everywhere — setting a reference for a sensor or ADC, biasing a transistor, or scaling a high voltage down to a meter-safe level. The key practical point is loading: a divider is only accurate when the current it draws is small compared with the current through R2. That's why this tool reports the loaded value and the drop; a low-impedance load pulls Vout well below the unloaded figure, the most common cause of "my divider isn't working" bugs.