Electrical Calculators

ABOUT THESE TOOLS

These calculators cover the sizing and code-check math electricians run every day: voltage drop on long feeder and branch runs, conductor ampacity after temperature and conduit-fill derating, conduit fill against the 40% limit, box fill allowances, motor full-load amps, transformer kVA, generator sizing with motor inrush, dwelling and commercial service loads, and the multiplier-and-shrink arithmetic of conduit bending.

The governing standard throughout is the National Electrical Code (NFPA 70). The ampacity tool works from NEC Table 310.15(B)(16) with the correction and adjustment factors, box fill follows the 314.16 allowances, conduit fill uses the Chapter 9 tables, and the voltage drop check is measured against the NEC’s 3% branch-circuit recommendation. Every tool states its method so you can verify it against the code edition your jurisdiction has adopted — these are working aids for licensed electricians, not a substitute for the code book or the AHJ.

Each calculator is free, runs in the browser with no account, and pairs with the NORDIX reference charts — wire ampacity, conduit fill, and ground wire sizing look-up tables — when you need the table itself rather than a computed answer.