from wire size to voltage drop — precise, and honest about the code.
Every tool prints its formula and the NEC table behind it — so you can check the number and hand it to an inspector.
→Find the right AWG and check drop % for any run — copper or aluminum, single or three phase.
Open calculator Calc 02Enter any two of volts, amps, ohms, or watts and get the other two instantly, with the equations shown.
Open calculator Calc 03NEC 310.16 ampacity with ambient-temperature correction and conductor-bundle derating.
Open calculatorCheck conductor fill against NEC conduit tables for EMT, PVC, and rigid. In the workshop now.
Coming soonMost online calculators give you a number and hope you trust it. Every Voltbench tool shows the formula, the NEC table it references, and the assumptions it makes — then says plainly where a licensed electrician needs to sign off. Useful, checkable, and honest about its limits.