Calculate a voltage divider's output.

Two resistors in series carry the same current. The voltage across each resistor is proportional to its share of the total resistance, so the output across R2 is a fraction of the input.

With a 12 V input and two equal 10 k ohm resistors, the unloaded output is 6 V. The divider current is 0.6 mA, and each resistor dissipates 3.6 mW. In the loaded example, another 10 k ohm resistor connects across R2. The two lower resistors act like 5 k ohms, reducing the output to 4 V. Source current rises to 0.8 mA; R1 dissipates 6.4 mW and R2 dissipates 1.6 mW. The load also draws 0.4 mA.

The output resistance shown by the calculator is R1 and R2 in parallel. It helps describe how strongly the divider can hold its intended voltage when another circuit is connected.

A voltage divider is useful for references, biasing, and reducing signals when the receiving circuit draws little current. It wastes some current continuously and its output changes with the load.

Use a regulator, converter, or properly designed power circuit when a device needs stable power. Also verify resistor tolerance and choose a power rating comfortably above the calculated dissipation.

Safety note: This educational calculator is for low-voltage DC circuits. Do not use it to design mains-powered or safety-critical equipment.