VoltCal Electrical Calculator

VoltCal is a free toolkit of electrical engineering calculators built for practicing engineers, designers, and students. No login or sign-up needed. Open a calculator, enter your inputs, and get results with the standard clauses and assumptions shown. WHAT'S INSIDE Power system studies - Short-circuit calculation (IEC 60909 and ANSI/IEEE C37) - Protection relay coordination with a time-current curve chart - Harmonic filter sizing (IEEE 519, IEC 61000-3-2) - Insulation coordination (IEC 60071-2) - Motor acceleration and starting voltage dip Cables and distribution - LV and MV cable sizing: ampacity, voltage drop, and short-circuit withstand - Cable schedule and material take-off (MTO) generator - Cable tray fill and conduit fill - Busbar sizing - LV panel board distribution schedule Protection, earthing, and safety - Earthing and grounding design (IEEE 80) - Lightning protection risk assessment and LPS design (IEC 62305) - Hazardous area classification and Ex equipment selection (IEC 60079) - IP code reference and compliance check (IEC 60529) Power supply and facilities - AC UPS and DC UPS (battery and charger) sizing - CT and PT/VT instrument transformer sizing - Electrical room heat load and battery room ventilation - HV motor efficiency classification (IEC 60034-30-3) - Solar PV suite: string, inverter, battery bank, DC cable, and protection sizing FEATURES - Calculations follow published IEC, IEEE, NEC, and other standards, with the references shown - Export professional PDF reports (and Excel for schedules) - Works on phone and tablet - Free to use, supported by ads WHO IT'S FOR Electrical engineers in oil and gas, data centers, industrial plants, utilities, and EPC projects, plus consultants, contractors, and engineering students. IMPORTANT Results are for design guidance and preliminary sizing. Always verify critical designs against the applicable standards and project specifications, and have them reviewed by a qualified engineer before use. Have a suggestion or found an issue? Use the in-app feedback form.