Whole-House Generator Cost: What You'll Actually Pay

A whole-house standby generator runs roughly $6,000 to $28,000 installed, and most homes land in the $9,500–$18,000 band for an 18–22 kW unit — the size that covers a typical single-family home. The equipment itself is only about half the project; the other half is the transfer switch, electrical work, fuel plumbing, a pad to sit it on, and permits. That second half is why two identical generators can cost thousands apart on two different properties.

This guide breaks down installed costs by generator size, what moves the number up or down, what quotes tend to leave out, what it costs to own year after year, and — honestly — when the number isn't worth paying. If you're still choosing between the two generator types, the home backup power overview covers both.

The short answer: installed cost by size

Generator size	What it covers	Typical installed cost
10–14 kW	Essential circuits: well pump, fridge, furnace blower, lights	$6,000–$12,000
18–22 kW	Whole home for most houses, including central AC	$9,500–$18,000
24–26+ kW	Large homes, multiple AC units, electric heat, shops	$13,000–$28,000+

These bands come from national cost guides and dealer-published breakdowns — vendor and marketplace estimates, in other words, not neutral data. (Angi, one of the most-cited cost sources, is itself a lead-generation marketplace.) They're solid for budgeting, but real quotes vary by region, site conditions, and installer — get three local quotes before spending. One guide puts a complete 14–22 kW install at $9,500–$15,000 under standard conditions, another at $9,700–$18,500 for 16–22 kW systems. The top end stretches higher when the site is difficult: long gas runs, panel upgrades, or unusual permitting can push a project past $24,000.

A note on the 24–26 kW line: 26 kW is about the ceiling for air-cooled residential units. Above that you're into liquid-cooled machines (Generac's Protector line, for example, runs 22–60 kW). They cost more and drink more fuel, but they run quieter and handle heavy, sustained loads — they're built for big houses and small commercial jobs, not the average rural home.

What moves the number

Every range above comes with a list of what pushes you toward the top or the bottom of it:

• Unit size. The generator itself is the biggest single line item — a 26 kW unit costs meaningfully more than a 14 kW one, and everything downstream (bigger transfer switch, heavier wiring, more fuel) scales with it.
• Fuel type and gas-line trenching distance. This is the swing item nobody budgets for. A short tap into an existing natural gas line might run $500–$1,500. A long trench from a propane tank to the generator — or buying and setting the tank itself — can add thousands. The closer the unit sits to both the fuel supply and the electrical panel, the cheaper the install.
• Electrical panel upgrades. If your service panel is old, undersized, or full, the electrician has to fix that before the transfer switch goes in. This is often the surprise line item.
• Concrete pad or composite base. The unit needs a level, stable foundation — $200–$1,500 depending on whether it's a preformed composite pad or a poured concrete one.
• Permits and inspections. Typically $100–$800, and this one is genuinely jurisdiction-dependent: some towns are a quick permit, some want engineered plans and multiple inspections.
• Region and labor rates. Electricians and gas fitters charge different rates in different markets, and rural travel time shows up in quotes too.
• Brand tier. Generac, Kohler, Briggs & Stratton, and Cummins all play in this space. Dealer support, warranty terms, and monitoring features vary — buy the dealer as much as the unit.

What's inside a typical quote

A complete installed quote is a bundle of line items. Here's what each one usually runs, so you can see which part of your quote is doing the damage:

Line item	Typical range
Generator unit (18–22 kW)	$4,500–$8,000
Automatic transfer switch	$700–$1,800 (up to ~$3,000 for large service-rated units)
Electrical labor and materials	$1,800–$6,000
Gas piping and connection	$800–$2,500
Propane tank purchase/set (if needed)	$1,000–$3,500
Concrete pad or composite base	$200–$1,500
Permits and inspections	$100–$800

Rule of thumb from the dealer world: the equipment is roughly half the project, installation is the other half. If a quote looks wildly cheaper than these bands, something in the right-hand column is probably missing — which brings us to the next section.

What quotes often leave out

These are the gotchas that turn a $12,000 quote into a $16,000 project:

• Trenching beyond a basic stub. Many quotes include a short gas-line run. A 100-foot trench across the yard to reach the propane tank is a different job, and it's often priced separately or not at all.
• Panel or service upgrades. The quote assumes your electrical service can accept a transfer switch. If it can't, that's a separate electrical project.
• Permits. Some quotes list them, some don't. Either way you (or the installer) pay the town.
• The first propane fill. A 500-gallon tank takes 400 usable gallons at the standard 80% fill. At the EIA's recent national average of about $2.67 per gallon for residential propane, that's roughly $1,070 of fuel on day one — before the unit ever runs an outage.
• Restoring the yard. Trenching tears up lawn and landscaping. Almost nobody puts the fix-up in the quote.
• The starter battery. It's a wear item, replaced every few years — some service plans bundle it, some don't. Ask.

The cheaper path: portable + manual transfer switch

Not everyone needs automatic whole-house coverage. The portable route, established on this site:

Setup	Typical cost
Portable generator (extension cords only)	$500–$2,500 for the unit
Portable + manual transfer switch	$900–$4,000 total

For that money you get real capability — the well pump, fridge, furnace blower, and lights — as long as you're home to start the unit and flip the switch. It's the honest answer for occasional, short outages on a budget. The portable vs. standby comparison walks through the trade-offs, and the sizing guide will tell you whether a portable can actually start your well pump.

Ongoing costs: maintenance

A standby generator is not a buy-it-and-forget-it appliance. It needs a yearly service — oil, filters, spark plugs, battery check, and a load test — and skipping it is how units fail to start during the one outage that matters.

• Professional service plan: $300–$600 per year is the typical band for residential units. Published dealer plans land right in it: about $369/year for a basic annual plan, $318/year for a standard plan on units 22 kW and under, stepping up to $465/year for 24 kW and over. Deluxe plans with semiannual visits run $600–$840/year.
• One-off visits: $150–$400 per visit if you're not on a plan. Cheaper only if you never miss one — and most people miss them, which is the point of the plan.

Budget $300–$500 a year for maintenance on a typical residential unit and you won't be surprised. Keep up the annual service and replace the starter battery on schedule — a dead battery is the most common reason a standby unit fails to start.

Ongoing costs: fuel

This is where the spec sheets earn their keep. Generac publishes fuel consumption for every Guardian model at half and full load — here are the numbers, straight from the manufacturer's specs:

Unit	Propane, 1/2 load	Propane, full load	Natural gas, 1/2 load	Natural gas, full load
10 kW	0.97 gal/hr	1.48 gal/hr	101 cu ft/hr	127 cu ft/hr
13 kW	1.54 gal/hr	2.45 gal/hr	154 cu ft/hr	225 cu ft/hr
16 kW	1.70 gal/hr	2.99 gal/hr	182 cu ft/hr	245 cu ft/hr
20 kW	2.37 gal/hr	3.56 gal/hr	204 cu ft/hr	301 cu ft/hr
22 kW	2.53 gal/hr	3.90 gal/hr	228 cu ft/hr	327 cu ft/hr

Now convert to dollars using current EIA fuel prices. Residential propane recently averaged about $2.67 per gallon nationally (EIA, end of the 2025–26 heating season — it runs over $3.50 on the East Coast and under $2.20 in the Midwest, so check your region). Residential natural gas averaged about $14.50 per thousand cubic feet in 2024 (EIA).

For the popular 22 kW unit at half load, that works out to:

• Propane: 2.53 gal/hr × $2.67 ≈ $6.76/hour
• Natural gas: 228 cu ft/hr × $0.0145 ≈ $3.31/hour

Two things fall out of that math. First, natural gas is roughly half the operating cost of propane when you have it — and it never needs a delivery truck. Second, a multi-day outage on propane is a real fuel bill: 48 hours at half load burns about 120 gallons, or roughly $320 at national-average propane prices. Size your tank to your realistic outage length, not your optimistic one — a 500-gallon tank's 400 usable gallons gives a 22 kW unit roughly 150 hours at half load.

The weekly exercise cycle

Standby units self-test on a schedule — Generac's Quiet-Test runs at reduced RPM for a few minutes, on a weekly, biweekly, or monthly schedule you choose. The fuel cost of this is trivial. Generac's liquid-cooled spec sheets publish consumption "at exercise speed" — about 0.5 gallons per hour of propane on a 22 kW unit — which works out to roughly a few gallons a year of weekly test runs. It's noise next to outage fuel. What matters isn't the cost, it's that the feature is actually enabled: an exercise cycle that catches a dead battery or a fault code in March is worth more than the fuel it burns.

A 10-year ownership example

Putting it together — this is an illustrative example, not a quote. Assumptions are stated so you can adjust them to your situation:

	Assumption	10-year total
Installation (22 kW, typical site)	$13,000	$13,000
Annual service plan	$400/yr	$4,000
Outage fuel (propane)	40 runtime hrs/yr at half load, $2.67/gal	$2,700
10-year total		~$19,700

Change the assumptions and the answer moves — natural gas roughly halves the fuel line, and a difficult install adds thousands up front. The structure of the number doesn't change, though — the install dominates, maintenance is the steady drumbeat, and fuel only matters in proportion to how often the grid actually fails you.

When the number isn't worth it

Honest section, as always. A standby generator is a lot of money for something that sits idle, and for some households the math genuinely doesn't close:

• You lose power rarely and briefly. If your outages are measured in hours per year, a portable and a manual transfer switch — or even just extension cords — covers the real risk for a tenth of the price. The automatic start is a luxury, not a necessity.
• You have nowhere sensible to put it. Tight lots, strict setbacks, HOA rules, or a panel on the wrong side of the house can turn a $13,000 project into a $20,000 one. At some point the site is telling you no.
• Your fuel situation is bad. No natural gas on the road, no room for a propane tank, and no appetite for managing deliveries? A standby unit you can't fuel is yard art. The portable route (dual-fuel, small tank) stays viable here.
• You're buying it for resale value alone. A standby generator is sometimes cited as adding 3–5% to a home's value, but that's a rule of thumb from real-estate professionals, not a guarantee — and it's strongest in outage-prone markets where buyers already want one. Don't spend $15,000 to chase a speculative bump.
• The rest of the house isn't ready. A generator powers the well pump; it doesn't fix a failing pump, a bad pressure tank, or a septic system with non-electrical problems. Fix the underlying systems first.

For everyone else — frequent or long outages, medical equipment, a home office that can't go dark — the standby is the gold standard for a reason. Just go in knowing the whole number, not the equipment price.