Ohm's LawCalculator
Solve voltage, current, resistance, and power from any two known circuit values before checking voltage drop or wire size.
Enter any two positive values and solve the remaining voltage, current, resistance, and power values. Use the result as a quick load check before running voltage drop, wire sizing, or conductor table lookups.
Calculator Inputs
Provide any two known circuit values
Ohm's law is a circuit relationship, not an NEC sizing rule. Use calculated current as an input to ampacity, conductor sizing, overcurrent protection, and voltage-drop checks.
Solved Values
Voltage, current, resistance, and power
Input value
Input value
Calculated value
Calculated value
Core Formulas
Use the Result in Circuit Design
Ohm's law is often the first calculation. The next step is checking conductor resistance, voltage drop, ampacity, and applicable NEC constraints for the installation.
AC Voltage Drop Calculator
Move from load current and voltage to a full AC voltage-drop check.
DC Voltage Drop Calculator
Use current, voltage, and circuit length for battery, PV, and control circuits.
Wire Size Calculator
Convert the calculated current into a practical conductor size recommendation.
Wire Tables
Compare conductor resistance and ampacity values for common AWG and kcmil sizes.
NEC Standards
Review code context before using calculated load current for final circuit design.