PowerSizing is a side project, not a company. It started because I kept running into the same frustration: you want a rough answer — how big a battery do I need, does solar pencil out at my utility rate, what happens if the grid goes down for three days — and either the tools available required a consultant, or they gave wildly different answers depending on which page you landed on.
The goal here is to fix that for the specific domains I know: home energy storage, solar, backup power, RV and van electrical systems, home electrical planning, and homelab/rack infrastructure. The calculators are built to give a fast, defensible first-pass answer that you can take into a more detailed design or a conversation with an installer.
Who this site is for
If you're a homeowner comparing battery quotes, an RV owner sizing an off-grid system, someone planning for outages, an electrician pre-qualifying a panel upgrade path, or a homelab builder checking UPS and rack power — this site is built with you in mind. You probably already understand the concepts; you just need the numbers without having to set up a spreadsheet every time.
What the calculators actually do
They handle the math for the most common planning questions in each domain. They're deliberately opinionated about defaults — most users don't need to tune every parameter — but the methodology page documents all the formulas and source assumptions so you can audit any result. Related tools share consistent assumptions so you don't get contradictory outputs depending on which calculator you used.
The trade-off is that these are planning tools, not engineering deliverables. They're designed to narrow your options and give you something to take into the next conversation — whether that's with an installer, an AHJ, or your own spreadsheet.
What the site is not
PowerSizing is not a licensed engineering firm. It does not produce stamped drawings, code-compliant designs, or installation certifications. Outputs are estimates based on standard formulas and generalized assumptions.
Electrical work — especially anything connected to the utility grid, a main panel, or high-voltage DC systems — carries real risk of fire, equipment damage, shock, and injury. Before purchasing equipment or beginning any installation, you should verify the design with a licensed electrician or solar installer, check applicable local codes and utility interconnection rules, and confirm product specifications directly with manufacturers. Calculator outputs are a starting point, not a sign-off.
Affiliate links and advertising
Some pages link to products or retailers using affiliate links. If you purchase through one of those links, PowerSizing may earn a small commission at no additional cost to you. Those links don't influence the calculator formulas or which products appear in results — the math is the math. Display ads may also appear on some pages. See the privacy policy for more on how that works.
Contact
Bug reports, calculator requests, and content questions go to contact@powersizing.com. I read everything, though response time varies.