Our Mission
Home Generator Calculator exists to answer one question clearly and honestly: what size generator do I actually need?
That sounds straightforward, but when you search for the answer online you typically hit one of three walls: manufacturer pages that steer you toward their most expensive model, lead-capture forms that turn your email address into a sales funnel, or generic tables that leave out the most important calculation — startup surge loads.
We built Home Generator Calculator so that anyone facing a power outage — whether from a hurricane, winter storm, or grid failure — can get a fast, accurate, unbiased answer with no strings attached.
What We Build
Every tool on Home Generator Calculator is:
- Free — no subscription, no trial, no paywall
- Private — all calculations run in your browser; nothing is sent to a server
- Unbiased — we are not affiliated with any generator brand or retailer
- Accurate — formulas account for startup surge loads, fuel efficiency curves, and NEC voltage-drop standards
Our Tools
Generator Size Calculator
Add your appliances and get a precise watt total with surge margin built in.
Runtime Estimator
Find out how long your generator will run on one tank of fuel at any load level.
Fuel Cost Calculator
Project your total fuel spend for any outage duration at current gas prices.
Extension Cord Gauge
Find the correct AWG gauge to prevent overheating and voltage drop.
How We're Funded
Home Generator Calculator is funded entirely by display advertising through Google AdSense. When you use our tools, Google may show relevant ads alongside the content. We do not have sponsored content, affiliate links, or any financial relationship with generator manufacturers or retailers.
We have deliberately excluded all dark patterns: no email gates, no mandatory account creation, no pop-ups, no interstitials. The ads that appear are standard display ads from Google's advertising network. This simple, honest model lets us keep every calculator free forever.
Accuracy & Limitations
Our calculators use industry-standard wattage figures and NEC guidelines. All generator size outputs include a 20% safety buffer above the calculated peak load, which is consistent with best practices from electricians and generator technicians.
Appliance wattage varies by manufacturer, model year, and operating conditions. The figures we use are mean values drawn from published manufacturer data and recognized reference sources including the U.S. Department of Energy's appliance energy use database. For permanent standby generator installations, always work with a licensed electrician who can perform a load calculation specific to your home.
Questions or Feedback?
Found an error in our wattage data? Have a suggestion for a new calculator? We genuinely want to hear from you — accurate data makes the whole site more useful.
Contact UsDisclaimer: All calculator outputs include a 20% safety buffer and are intended as general guidance only. Wattage figures are approximations based on industry averages. Actual loads vary by appliance brand, age, and condition. Always consult a licensed electrician for permanent installations. Home Generator Calculator is not liable for equipment damage, bodily injury, or financial loss arising from use of these tools.