Whole-House Generator Cost Estimator
Enter your home size and fuel to size a standby generator and price it installed.
Runs entirely in your browser — your numbers never leave this page.
How it works
Standby generator = right-sized unit + fuel infrastructure + transfer switch:
- Sizing: essential circuits ~1 kW per 200 sq ft; whole house ~1 kW per 120 sq ft. Oversizing wastes fuel and money.
- Natural gas: cheapest install if you have service — but verify meter capacity.
- Propane: needs a 250–500 gal tank (+$1,500 install) — the rural default.
- Diesel: longest-running, noisiest, fuel goes stale — best for long outages.
- Portable alternative: a $1,000–2,500 portable + manual transfer switch covers essentials for a tenth of the price — if you're home to start it.
- Maintenance: ~$400/year — oil, filters, battery, and the weekly self-test sip of fuel.
Frequently asked questions
How much does a whole-house generator cost?
Roughly $10,000–18,000 installed for a typical home — unit (~$420/kW) plus $4,500–8,000 installation.
What size generator do I need?
Essential circuits: ~1 kW per 200 sq ft. Whole house: ~1 kW per 120 sq ft. A 2,500 sq ft home: ~13 kW essential, ~22 kW whole.
Natural gas vs propane?
Natural gas: cheapest install with existing service. Propane: needs a tank, the rural default. Diesel: longest runtime, most maintenance.
How long can it run?
Natural gas: indefinitely (utility-dependent). Propane 500-gal: ~7–10 days at half load. Diesel: days, limited by tank.
Is a portable generator enough?
For essentials, yes — $1,000–2,500 plus a transfer switch. Standby wins on automation: it starts itself whether you're home or not.
What is an automatic transfer switch?
It detects outages, starts the generator, and switches your panel over — then back when power returns. Included in pro installs.
How much maintenance?
About $400/year: oil/filter service, battery replacement every 3–4 years, and weekly exercise-cycle fuel.
How loud are they?
65–75 dB at 20 ft — like a loud conversation. Check setback rules and neighbor relations.
Does it add home value?
In outage-prone areas, yes — roughly 50% of cost. Elsewhere it's a lifestyle/insurance purchase.
Do I need a permit?
Yes — electrical and often gas/plumbing permits, plus inspections. Your installer usually handles it.