Electrical Calculator

Solve for voltage, current, resistance, or power from any two known values. The core relations are V = I × R, P = V × I, P = I² × R, and P = V² ÷ R. Supports DC and single-phase AC, with power factor input for true power calculations.

Calculate voltage drop with VD = (2 × K × I × L) ÷ CMA for single-phase and VD = (√3 × K × I × L) ÷ CMA for three-phase. K is 12.9 for copper and 21.2 for aluminum. The app then selects the smallest AWG or kcmil conductor that keeps drop within the target percentage and satisfies NEC 310.16 ampacity.

Size overcurrent protection with the NEC continuous load rule: Idesign = 1.25 × Icontinuous + Inon-continuous. Then select from NEC 240.6 standard breaker sizes: 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125 A and upward. The next standard size up rule applies for conductors 8 AWG and larger.

Check conduit fill against NEC Chapter 9, Table 1 limits: 53% for one conductor, 31% for two, and 40% for three or more. For motors, use NEC Table 430.250 full-load current values, then apply the 125% continuous-duty factor for branch-circuit conductors and overcurrent protection.

Estimate daily, monthly, and annual energy use with kWh = (Watts × Hours) ÷ 1,000, then multiply by the local tariff for cost. Run appliance-level scenarios and compare LED, HVAC, or motor upgrade payback periods. Includes a simple payback calculator for efficiency investments.

Generate professional PDF calculation sheets showing input values, formulas used, results, and NEC article references. Export to CSV for project files or client proposals. All calculations run on-device with no internet required, so the app works in basements, service rooms, and remote sites.