About
Browser-side sizing tools for batteries, power stations, and the loads they serve — with the formula and the source on the page.
JouleCalc is a small calculator site I built as a software engineer who works with energy-storage numbers and was tired of tools that hide the equation, invent a default, or silently round a series string that does not divide. The site is English-only in year one, aimed at U.S. households, RVs, and small off-grid systems. Pages stay short. The calculator is the point.
Three rules run every tool. If the published data is not enough, the tool refuses — it will not invent a surge rating or a wire size above the table. Every default has a source on the page (DOE, EIA, NEC, NREL, or a manufacturer datasheet) and the date we captured it. There are no accounts, no cookies we set, and no backend: the math runs in your browser, and a share link is just the numbers you typed.
If a figure looks wrong, that is the mail I want. Use the contact address. Product matches, when they appear, are sorted smallest-capable-first from a table we maintain — not a paid ranking.