About
A set of electrical calculation tools built around one idea: a calculator should show its working.
What this is
Voltage Drop Solver calculates voltage drop, conductor size and maximum cable length for DC, single-phase and three-phase circuits. It runs entirely in your browser, needs no account, and stores nothing about you.
Why it exists
Most voltage drop calculators return a number and stop. That is fine until the number surprises you, and then you have no way to tell whether the tool is wrong, your input is wrong, or your expectation is wrong.
So every result here comes with the formula it used, the values substituted into it, the intermediate steps, and a citation for the reference data behind it. You can check the arithmetic by hand if you want to. Several of the site’s own tests do exactly that.
Who it is for
Electricians sizing a run on site. Engineers checking a feeder at a desk. Students who need to see the substitution rather than just the answer. Solar and marine installers working at 12 V and 24 V, where a fraction of a volt is a real percentage. Anyone who has been told 3% and wants to know where that came from.
What it will not do
It will not tell you an installation is code compliant, because no calculator can. Voltage drop is arithmetic; compliance depends on the code edition adopted where you are, the conditions of the installation, and the judgement of a qualified person. The tools keep the engineering calculation and the code table look-up visibly separate, and label both.
It also will not invent data. Where a value is published, it is cited. Where a value is computed, the derivation is shown. See data, assumptions and method for all of it.
How it is built
Static pages with a small amount of JavaScript in the calculators and none anywhere else. The calculation engine is a separate module with no interface code in it, which is what makes it testable: the same functions the browser runs are the ones the test suite checks against hand calculations and against the published effective-impedance column of the reference tables.
Corrections
If a number here is wrong, it is worth fixing. Reports that name the specific value, what it should be, and where that comes from get acted on fastest. See contact.