Disclaimer

Last updated: September 2026. Please read this page carefully before using our calculators.

Educational information only

All content on WattGuide — calculators, articles, tables, and examples — is published for general educational purposes. It is not electrical or energy advice and is not a substitute for a qualified professional. We are not licensed electrician or HVAC contractors, and no client or advisory relationship is created by your use of this Site.

Our calculators use standard industry rules of thumb — 20 BTU per square foot of cooling base, nameplate wattage for appliance costs, published sun-hours for solar estimates. Buildings vary so much around these baselines that professionals measure, model, and then still argue.

Generator and solar installations involve your electrical panel, local codes, and sometimes utility permission. Use these numbers to size your thinking, then have a licensed electrician or installer verify anything that touches wiring.

Accuracy of calculations

We implement well-known, publicly documented formulas (see the methodology section on each calculator page and DOE and EPA public efficiency guidance as applicable). Even correctly implemented formulas produce estimates that depend on your inputs and assumptions. Real-world outcomes vary. Do not rely on a single web tool for a consequential decision.

Advertising disclosure

WattGuide is funded by display advertising served through Google AdSense. Advertisers have no influence over our content, formulas, or editorial choices, and placement of an ad is not an endorsement.

Errors and corrections

If you spot an error, please email hello@wattguide.com with the inputs you used. Verified corrections are published promptly.