WireGaugeCalc Calculators
Every page opens with the calculator embedded and the NEC article cited. Pick the one you need, enter your values, and read the answer. Free, no signup, works offline.
Wire & conductor size
22 pagesPick the right gauge for a load, service, or subpanel from the NEC 310.16 ampacity tables.
Wire Gauge Calculator
100 Amp Wire Size
50 Amp Wire Size
200 Amp Wire Size
40 Amp Wire Size
What Size Wire For 100 Amp Service
Wire Size For 20 Amp
60 Amp Wire Size
30 Amp Wire Size
100 Amp Service Wire Size
Dc Wire Size Calculator
What Size Wire For 20 Amp Circuit
200 Amp Service Ground Wire Size
Amp Wire Size
Range Wire Size
400 Amp Wire Size
Grounding Wire Size
100 Amp Wire Gauge
Ground Wire Size For 100 Amp Service
Sizing Ground Wire
150 Amp Service Wire Size
Nec Wire Size
Voltage drop
3 pagesCheck the drop on a run and see whether it stays inside the 3% guideline.
Conduit fill
5 pagesFill percentage for EMT, PVC, and RMC from the NEC Chapter 9 tables.
Box fill
1 pagesMinimum box volume from the conductor, device, and ground allowances in 314.16(B).
Ampacity & derating
2 pagesAllowable ampacity for a conductor at its termination temperature.
More calculators
7 pagesOhm’s law and the rest of the on-the-job math.