Ohm's Law Calculator

Ohm's Law is named after Georg Simon Ohm (1789–1854), a German physicist who first described the relationship between voltage, current, and resistance in 1827 in his work Die galvanische Kette, mathematisch bearbeitet (The Galvanic Circuit Investigated Mathematically).

Ohm's work was initially met with skepticism. The scientific establishment, particularly in Germany, rejected his findings for years. It wasn't until the 1840s that his contributions were widely recognized, when the Royal Society of London awarded him the Copley Medal in 1841.

The unit of electrical resistance, the ohm (Ω), was named in his honor in 1881 at the International Electrical Congress. Today, Ohm's Law remains one of the most fundamental and widely used equations in electrical engineering, forming the basis for circuit analysis, power calculations, and electronic design.

This Ohm's Law calculator solves for any unknown value (Voltage, Current, Resistance, or Power) given two known values. Unlike basic calculators that only handle V = IR, this tool integrates the power equation (P = VI) to provide complete circuit analysis from any combination of two inputs.

The interactive circuit visualization updates in real-time, showing current flow direction and magnitude. All calculations run entirely in your browser — no data is sent to any server. The Show Work section provides a transparent step-by-step breakdown so you can verify the math and learn the process.

This tool is designed for students, hobbyists, and professionals working with DC circuits. For AC circuit analysis involving impedance, reactance, and phase angles, a dedicated AC circuit calculator would be more appropriate.