Electrical & Off-Grid Power Calculators
Free, no-signup calculators for wire sizing, voltage drop, ampacity, conduit fill, Ohm's law and breaker size — plus solar arrays, battery banks, inverters, generators, RV 12V wiring and energy cost. Each tool ships with the formula, a worked example, a reference table and a source. Results are estimates for planning and education.
Results are estimates for planning and education, based on your inputs and standard engineering values (AWG resistance, NEC ampacity, resistivity). Electrical work can be dangerous and is governed by the NEC and your local code — verify all sizing with a licensed electrician and your authority having jurisdiction (AHJ). Not a substitute for professional design.
Topics
Tables and guides
- Reference tables — AWG wire chart, NEC ampacity, conduit fill, voltage drop, resistivity, peak sun hours and appliance wattage.
- Guides — the why behind each calculation, step by step.