Electrical Calculators — Voltage Drop, Wire Size, Conduit Fill & More
Twelve calculators built around the tables electricians actually work from — NEC 310.16 ampacity, Chapter 9 conduit fill, 314.16 box fill, 240.4(D) small-conductor caps, 210.20(A) continuous-load sizing and the hand-bender take-up/multiplier/shrink set. Every result shows its rule citation so you can defend the number at inspection. No app, no sign-up, no upload: open the page on the job site and run the math.
More Electrical Calculators
Voltage Drop Calculator
Enter voltage, load amps and run length — get the voltage drop in volts and percent for every wire size, with the smallest size that holds 3%.
Wire Size Calculator
Enter load current and terminal temperature rating — get the minimum AWG by ampacity, with the 240.4(D) small-conductor caps already applied.
Conduit Fill Calculator
Pick conduit type and trade size, list your wires — get the fill percentage against the NEC 40% limit and the max count of that wire.
Box Fill Calculator
Enter the box volume and everything that lands in it — wires, clamps, devices, grounds — and see the 314.16 cubic-inch tally with pass/fail.
Breaker Size Calculator
Enter watts, voltage and whether the load is continuous — get the breaker size, the 125% design current and the minimum copper at 75°C.
Residential Load Calculator
Enter square footage and major appliances — get the demand load in VA and the service size (100/125/150/200 A) the numbers support.
Generator Size Calculator
List what must run in an outage with each item's starting watts — get running watts, peak demand and the suggested nameplate kW.
Conduit Bending Calculator
Pick a bend — 90° stub, offset or 3-point saddle — enter the rise or obstruction, and get every pencil mark plus the shrink.
Stub-Up Calculator
Enter the stub height and conduit size — get the take-up, the exact mark from the end of the conduit, and the full take-up table.
Offset Bending Calculator
Enter the offset rise and pick an angle — get the distance between marks from the multiplier table and the shrink to add back.
3-Point Saddle Calculator
Enter the obstruction's width and height — get the saddle depth, center-to-side mark spacing, and the total shrink for each angle combo.
Conduit Bending Multipliers Chart
The whole hand-bender cheat sheet in one table: take-ups per size, offset multipliers, shrink per inch of rise, and saddle combos.