VoltDropCalc is a free collection of voltage drop and conductor sizing calculators for electricians, engineers, solar installers and serious DIYers. Every tool runs entirely in your browser — no logins, no uploads, no waiting.
The calculations are built on published NEC data: Chapter 9 Table 8 conductor resistance, Table 310.16 ampacities, and the Chapter 9 raceway fill tables. Where the math involves judgment — power factor approximations, derating methods — the methodology is stated openly on each tool page.
The site is built and maintained by Murugan Vellaichamy, a software engineer who builds fast, focused, browser-side utility tools. Found a bug or want a feature? Get in touch.