DC & AC · V = IR · P = VI · Z = √(R²+X²) · Power Triangle S / P / Q
DC Circuit
Direct Current · Ohm's Law · V = IR · P = VI
Fill in any two fields — the third is solved automatically. Power (P) is always derived from V and I.
Voltage — V
Current — I
Resistance — R
AC Circuit
Alternating Current · Impedance & Power Triangle · Z = √(R²+X²)
Fill in any two of V, I, Z — the third is solved automatically. Optionally expand the section below to enter R and X for a complete power triangle (S, P, Q, PF, θ).
Voltage — V (RMS)
Current — I (RMS)
Impedance — Z
Ohm's Law · Power Formula Wheel
Enter values — solved quadrant highlights
Disclaimer — Important
This calculator is an independent tool intended to assist electrical professionals. It provides general guidance based on fundamental electrical theory (Ohm's Law, Joule's Law, and AC circuit analysis) for educational and estimation purposes only. Results do not account for temperature coefficients, skin effect, conductor resistance, harmonic distortion, or installation-specific factors.
Results must be verified by a licensed electrical engineer or electrician and reviewed against applicable NEC 2023 (NFPA 70) articles, equipment listings, manufacturer specifications, and local codes before use in design, permitting, or construction.
This calculator does not evaluate conductor sizing (Article 310), voltage drop (Article 215), overcurrent protection (Article 240), or equipment short-circuit current ratings (SCCR). Always consult the adopted code edition and the authority having jurisdiction (AHJ) before finalizing any electrical design.
NEC® and NFPA 70® are registered trademarks and copyrighted publications of the National Fire Protection Association.