These five calculators cover the foundational relationships every electrical engineer must know. They are ideal for the fundamentals of engineering (FE) and principles and practice of engineering (PE) Power exam preparation. They are equally useful for solving real-world power engineering problems daily.
The calculators include Ohm’s Law, three-phase power, power factor correction, impedance, and transformer power rating calculations. Each one uses accepted industry formulas from IEEE Std 100, IEEE Std 141, and IEEE Std C57.12.00. The basics provide quick results; however, take into account the specific needs of what you intend to achieve.
Simply enter your known values and select your preferred units. The formula used is shown with every result — no black boxes. Whether you are a student or a licensed engineer, these tools are built for you.
Ohm's Law & DC Power
Solve for Voltage, Current, Resistance, or Power — enter any two known values
V = IR | P = VI = I²R = V²/RAll inputs converted to SI before calculation
Three-Phase Power
Real (P), Reactive (Q), Apparent (S) — balanced three-phase systems
S=√3·VL·IL | P=S·cosφ | Q=S·sinφPower Factor Correction
Capacitor bank sizing to improve lagging power factor (IEEE Std 141 §8.2)
Qc=P·(tanφ1−tanφ2)Enter real power and both power factors. Returns required capacitor bank — per IEEE Std 141 §8.2.
C=Qc×10⁶/(3·2πf·V²) [µF] — delta-connected bank | Target PF must exceed existing PF
Impedance (Z) Calculator
Series RLC impedance — magnitude, phase angle, rectangular & polar form
|Z|=√(R²+X²) | XL=2πfL | XC=1/(2πfC)XL=2πfL [Ω] | XC=1/(2πfC) [Ω] | Xnet=XL−XC
Transformer kVA Rating
Single-phase & three-phase — solve for kVA, Voltage, or Current
S3φ=√3·VL·IL | S1φ=V·IIFLA=S/(√3·VL) for 3φ | IFLA=S/V for 1φ