Ohm’s Law Calculator (V, I, R, P)

Ohm’s Law Calculator

Calculate voltage, current, resistance, and power instantly. Enter any two of the four electrical values — the calculator solves for the remaining two using Ohm’s Law (V=IR) and the power equation (P=VI). Supports unit prefixes from micro to mega for real-world engineering use.

Anwendung

Enter any two values — Voltage (V), Current (I), Resistance (R), or Power (P) — and the calculator instantly computes the other two. Select unit prefixes (mA, kΩ, mW, etc.) from the dropdown next to each input. Use preset buttons for common circuits like LED, USB, car battery, or household power. Results update in real-time as you type, with the formulas used shown in the output.

Merkmale

• Any-Two-In, Two-Out Solving — Enter any combination of two values (V+I, V+R, V+P, I+R, I+P, R+P) and get the remaining two calculated instantly.
• Unit Prefix Support — Select from µA to A, mΩ to MΩ, µW to kW, mV to kV. Results auto-format to the most readable prefix.
• Formelanzeige — Shows which formula was used (V=IR, P=VI, P=I²R, P=V²/R) and the calculation steps so you can verify the math.
• Quick Presets — Common circuit scenarios: LED circuit (5V/20mA), USB (5V/500mA), car battery (12V/10A), household mains (230V/10A).
• Smart Input Tracking — Visual distinction between user-entered values and calculated results. Editing a third field automatically drops the oldest input.
• Eingabevalidierung — Prevents negative values and warns on extreme or unrealistic combinations.

Ohm’s Law Formulas

Ohm’s Law and the power equation give us 12 formulas linking V, I, R, and P. Given any two, the other two can be derived:

• V = I × R — Voltage equals current times resistance
• I = V / R — Current equals voltage divided by resistance
• R = V / I — Resistance equals voltage divided by current
• P = V × I — Power equals voltage times current
• P = I² × R — Power equals current squared times resistance
• P = V² / R — Power equals voltage squared divided by resistance