Electrical calculators that show their working
Sizing answers for the field, with the arithmetic printed beside the result and the condition that decided it named out loud.
Voltage drop calculator
Volts lost over a run, and the smallest conductor that keeps you under a target. Copper or aluminum, single or three phase.
Voltage drop formula
The arithmetic, the resistivity behind it, and the check that the computation reproduces its published source.
Conduit fill calculator
Needs conduit interior areas and conductor outside areas from manufacturers published data. Sourceable, not yet sourced.
Not yetConductor ampacity
Blocked on data, not on rights: this site will not print a code table it cannot source. Arrives when a licensed copy is on the desk.
Not yetWhat makes these different
The charts that rank for these questions are almost all lead magnets. A wire distributor or a battery brand publishes a flat table because the table brings people who might buy something, and a flat table cannot answer a question that depends on conditions. So the conditions get dropped, and you get a number with no way to tell whether it applies to you.
These tools do the opposite. You get the number, then the arithmetic that produced it, then the constant that went into the arithmetic and where it was published — and a line saying which condition actually governed the answer. If you disagree with an assumption, you can see which one it was.
What is not here yet, and why
Conductor ampacity is the thing people ask for most and it is deliberately absent. The tables that answer it are published by a standards body, and this site will not print a number it cannot source. That page arrives when a licensed copy is on the desk, and not before.
Conduit fill is next. It needs conduit and conductor dimensions from manufacturers' published data, which is sourceable and not yet sourced.
How to check us
Every page names its source, its formula and its assumptions. The resistance figures are recomputed from published resistivity at every build and compared against the source document's own table — n=23 values, all within 1% — and the build fails if that stops being true. Nothing here is transcribed from memory.
Not affiliated with, endorsed by, or a publication of any standards body.