Electrical Calculators & Reference Tools
Start with your job, not with a formula. Pick what you are sizing, enter your numbers, and see the formula, the steps, and what would change the answer.
Formula shown • Steps shown • NEC tables where they matter • Works on mobile
Start With Your Job
What are you sizing today?
I need to size an EV charger circuit
Breaker, wire and voltage drop in 5 steps, including the 125% rule.
I need to run a subpanel feeder
Ampacity and voltage drop checked separately, with a 100 ft example.
I need to wire a well pump far from the panel
Why a long run needs a bigger wire than ampacity alone.
I need to power a detached garage
Feeder sizing plus the separate grounding and disconnect rules.
I need solar + battery for a van or RV
Panels from peak sun hours, battery from usable energy.
I need to size a motor circuit and breaker
Conductors at 125%, breakers at 250%, overload from the nameplate.
Tool Categories
Explore Electrical Utilities by Topic
Electrical Calculators
Ohm's law, power, voltage, current, and circuit resistance calculations.
Wire & Cable
Voltage drop over distance, conductor gauge sizing, and thermal ampacity.
Battery & Power
Battery runtime, required capacity (Ah/Wh), and inverter wattage sizing.
Solar & Off-Grid
Solar array sizing, peak sun hour production, and inverter headroom.
Motors & Protection
Motor full-load current, starter sizing, breaker selection, and overload settings.
Converters
AWG to mm², Watts to Amps, Volts to Watts, and kW to Horsepower.
Charts & Tables
Searchable AWG wire charts, battery state-of-charge, and schematic symbols.
Electrical Reference
Master formula cheat sheets, Ohm's law circle, and theory guides.
Calculators
Popular Electrical Calculators
Ohm's Law Calculator
Calculate Voltage, Current, Resistance, and Power simultaneously.
Voltage Drop Calculator
Compute line voltage drop, loss percentage, and load voltage for single & 3-phase.
Conduit Fill Calculator
Visual NEC Chapter 9 raceway sizer with 40% fill rule and jam warnings.
Motor Full-Load Current & Breaker Sizer
Size motor conductors (125%), breakers (250%), and fuses per NEC 430.
Wire Size Calculator (AWG & mm²)
Find recommended conductor gauges to stay within NEC 3% voltage drop limits.
Circuit Breaker Sizing Calculator
Determine standard breaker ampere ratings applying the 125% continuous rule.
Popular Unit Converters
Instant bidirectional electrical unit translations
Recently Added & Spotlights
Latest reference guides and interactive utilities
About VoltBase Pro
Engineered for Speed, Clarity, and Precision
VoltBase Pro was built because most online calculators give you a number and stop there. Here you also get the formula, the steps, and the one assumption that would change the answer, so you can check the result before you trust it.
- 100% In-Browser Computations: Zero backend latency or server round-trips.
- Formulas & Step-by-Step Transparency: Every calculation shows the exact physical formula and step derivation.
- Strict Mathematical Separation: Physical calculations are clearly separated from code-dependent regulatory rules.
Quick Platform Summary
- Calculators
- 23
- Converters
- 7
- Reference Charts
- 4
- Guides
- 15