Electrical Engineering Units & Formulas Reference Sheet

Every electrical engineer and apprentice needs a reliable formulas reference within arm's reach. This A4 portrait sheet consolidates the essential electrical engineering equations and unit conversions onto a single page. The top section covers the fundamental relationships: Ohm's Law (V=IR) in all rearrangements, the power triangle (P, Q, S, power factor), single-phase power (P = V × I × cosφ), and three-phase power (P = √3 × V_L × I_L × cosφ). The middle section presents working formulas for everyday design tasks: impedance (Z = √(R² + X²)), voltage drop for single-phase and three-phase circuits, prospective fault current (I_f = V / Z_s), transformer current relationships (I₁/I₂ = V₂/V₁), motor full-load current estimation, and capacitor sizing for power factor correction (Q_c = P × (tanφ₁ - tanφ₂)). The bottom section covers unit conversions that trip up engineers working across standards: AWG to mm² (with the most common sizes tabulated), HP to kW (1 HP = 0.746 kW), BTU/h to kW, and the full SI prefix scale from pico (10⁻¹²) through tera (10¹²). Each formula includes the variable definitions and SI units. A QR code links to the ECalPro calculator suite. Print this, laminate it, and tape it to your desk — you will use it every day.