About WattGuide

WattGuide is the homeowner's energy arithmetic: how big an AC, what that old fridge costs per year, what size generator survives a storm, and how many panels make the bill go away.

Home energy decisions are expensive on both sides: oversize the AC and you pay forever in comfort cycles; undersize the generator and you learn about it in the dark. The math for getting it right is public — DOE rules of thumb, nameplate wattages, local sun-hours — but it lives in fifteen different places.

WattGuide puts it in four calculators that show their formulas: BTU sizing with the climate and sun adjustments, appliance costs from real wattages, a generator checklist with surge watts handled properly, and a solar estimate built from your actual bill and roof.

We're homeowners, not installers — which is exactly why every page ends by telling you which numbers a professional needs to verify before money changes hands.

What makes WattGuide different

• Your numbers never leave your browser. Every calculator on WattGuide runs entirely on your device. We never see, store, or transmit the figures you enter — there are no accounts and no server-side processing of your inputs.
• Published methodology. Each calculator page explains the exact formula it uses and the assumptions behind it, so you can check our work or reproduce it in a spreadsheet.
• Free, forever, without a paywall. WattGuide is supported by advertising. There is no premium tier, no email gate, and no upsell.

Independence

WattGuide is an independent educational project. We are not affiliated with, endorsed by, or acting on behalf of any government agency, lender, insurer, or the organizations whose formulas and public data we reference (such as DOE and EPA public efficiency guidance). All trademarks and referenced standards belong to their respective owners.

Questions, corrections, or suggestions are genuinely welcome — get in touch.