How much does a whole-house generator cost installed?

A whole-house standby generator costs $7,000–$25,000 installed, including the unit, automatic transfer switch, fuel connection, concrete pad, and electrical work. Most homeowners with a 2,000–3,000 sq ft home land at $10,000–$16,000 for a 14–22 kW unit. Larger homes, complex electrical panels, or propane sites with tank installation push toward the top of the range.

What size generator do I need for a whole house?

A 2,000 sq ft home with central HVAC, a refrigerator, lights, and standard appliances needs roughly 10–14 kW to run everything simultaneously. A 3,000 sq ft home with a heat pump, well pump, or EV charger typically needs 18–22 kW. Add the running wattage of your HVAC system (typically 3,500–7,000W for central AC) plus 5,000W for essential circuits to estimate minimum capacity.

What is the difference between a standby generator and a portable generator?

A standby generator is permanently installed outdoors, connected to your home's electrical panel via an automatic transfer switch, and starts within seconds of a power outage with no homeowner action required. A portable generator runs on gasoline from portable tanks and must be connected manually. Standby generators cost 5–10 times more but provide seamless, automatic whole-home backup.

Natural gas vs. propane for a whole-house generator: which is better?

Natural gas is preferred where a gas line is available — it requires no fuel storage, has unlimited supply during most outages, and costs less per kWh than propane. Propane requires a 250–1,000 gallon on-site tank but is available in areas without natural gas service. Diesel offers high energy density but poses storage, degradation, and regulatory complications that make it uncommon for residential use.

Do I need a permit to install a whole-house generator?

Yes. Almost all jurisdictions require electrical and gas permits for standby generator installation. The electrical permit covers the transfer switch and panel connection; the gas permit covers the fuel line connection. Most jurisdictions also require setback review — typically 5 feet from windows and doors, 18 inches from combustibles. Permit costs run $100–$500 and are usually included in contractor quotes.

Whole-House Generator Installation Cost Guide (2026)

June 5, 2026 · Cost Guide · 6 min read

A whole-house standby generator costs $7,000–$25,000 installed in 2026, with most residential installations falling between $10,000 and $16,000 for a 14–22 kW unit. The cost spread reflects generator capacity, fuel type (natural gas, propane, or diesel), transfer switch complexity, site preparation requirements, and regional labor rates. Units for large homes, complex electrical panels, or propane-only sites with tank installation push toward the top of the range.

How Standby Generators Work

A standby generator is a permanently installed appliance that monitors utility power continuously. When grid power fails, the automatic transfer switch (ATS) disconnects from the utility grid and routes power from the generator to the home's electrical panel within 10–30 seconds. When utility power is restored, the ATS switches back and the generator shuts down after a cooldown cycle — all without homeowner involvement.

The automatic transfer switch is the most important component after the generator itself. It protects the generator from backfeeding into utility lines (a legal and safety requirement), manages the transition between power sources, and determines which circuits in your home are backed up. A whole-home ATS connects the generator to your full electrical panel; a partial-home or load-shedding ATS prioritizes specific circuits (HVAC, refrigerator, sump pump, lights) when the generator's capacity cannot run everything simultaneously.

Generator Sizing Guide

Undersizing a generator is the most common and expensive installation mistake — an undersized unit runs under sustained overload, burns more fuel, and fails early. Key loads to sum:

Air conditioning: 3,500–7,000W running (add 2–3× for startup surge)
Refrigerator and freezer: 600–800W running
Well pump: 750–1,500W running
Sump pump: 800–1,500W running
Whole-home lighting: 500–1,500W
Miscellaneous outlets and devices: 500–1,000W

A practical sizing guide by home size:

1,200–1,800 sq ft with gas heat: 10–13 kW — covers HVAC, refrigerator, lights, and standard outlets
2,000–3,000 sq ft with gas heat: 14–18 kW — adds well pump, multiple circuits
3,000–4,500 sq ft with heat pump or electric appliances: 20–26 kW — powers high-draw heat pumps and large HVAC systems
Homes with EV chargers or pool equipment: Add 7.2 kW per Level 2 charger and 1.5–3 kW for a pool pump; size up accordingly

Cost by Generator Size and Brand

Generator unit prices (equipment only, before installation) by capacity:

7.5–10 kW: $1,800–$3,000. Suitable only for partial-home coverage or very small homes.
14–18 kW: $3,500–$5,500. The most popular residential size range. Generac Guardian 16kW ($4,000), Kohler 14RESA ($5,200), Cummins RS17A ($5,000).
20–24 kW: $5,000–$8,000. Whole-home coverage for larger or high-consumption homes. Generac Guardian 22kW ($5,500), Kohler 20RESA ($7,500).
26–30 kW: $8,000–$12,000. Large homes, homes with electric heating loads, or light commercial use. Kohler 30RCL ($11,000), Cummins RS30A ($9,500).

Brand notes: Generac holds roughly 70% of the residential standby generator market and has the widest installer network. Kohler is widely considered the premium tier — better warranty terms (5-year residential), quieter operation, and higher build quality at a 15–25% price premium over Generac. Cummins offers comparable quality to Kohler with strong commercial service networks. Briggs and Stratton and Champion provide budget-tier options that are adequate but carry shorter warranty coverage (typically 2–3 years).

Full Installation Cost Breakdown

For a 16–18 kW natural gas generator in a typical installation, the full installed cost breaks down approximately as follows:

Generator unit: $3,800–$5,500
Automatic transfer switch: $600–$1,200 (whole-home ATS; more for load management systems)
Electrical labor (panel connection, transfer switch): $1,500–$3,000
Gas plumber (fuel line extension or connection): $500–$1,500
Concrete pad (typically 3×5 ft minimum): $300–$700
Permits: $150–$500
Total: $6,850–$12,400

Propane installations add the cost of a tank ($500–$2,500 to purchase or rent a 500-gallon tank) and propane line installation ($300–$800). Rural sites with long distances from the main gas line or complex panel configurations add $1,000–$3,000 to electrical labor.

Fuel Type Comparison

Natural gas is the dominant choice in areas with utility gas service. The advantages are decisive for most homeowners: unlimited fuel supply during outages (gas pipelines rarely fail during the weather events that knock out the grid), no fuel storage required, and the lowest cost per kWh. Generator output is typically 5–10% lower than rated capacity at natural gas pressure, but this is accounted for in standard residential sizing.

Propane is required where natural gas is unavailable. A 500-gallon tank holds roughly 150 hours of fuel at 50% generator load — adequate for most outage scenarios but requiring monitoring and potential mid-outage delivery during extended events. Propane costs more per kWh than natural gas in most markets and requires periodic tank inspection.

Diesel is rare in residential installations. Higher energy density than gas or propane, but diesel degrades in storage (requires additives for tanks held more than 12 months), is subject to stricter emissions regulations in some jurisdictions, and lacks the residential installer network of gas-fueled generators.

Permits and Setback Requirements

Generator installation always requires permits. A licensed electrical contractor must pull the electrical permit for the transfer switch and panel work; a licensed plumber or gas fitter must pull the gas permit for the fuel line connection. The generator must also meet setback requirements — typically 5 feet from windows and doors and 18 inches from combustibles, though local codes vary by jurisdiction.

Never attempt a whole-house generator installation without permits. Unpermitted generators are flagged during home sales, can void homeowner's insurance coverage for related damage, and create liability if a problem occurs. Our home renovation permits guide covers the permit process for major home systems installations. Generator installation is specifically listed in our projects you should never DIY guide — the combination of electrical panel work and gas connections makes this one of the higher-consequence projects to get wrong.

Tax Credits and Incentives in 2026

Whole-house generators fueled by natural gas, propane, or diesel generally do not qualify for the federal residential clean energy tax credit (Section 25D), which is restricted to solar, battery storage, wind, and geothermal systems. Generator installations paired with battery backup systems (Tesla Powerwall, Enphase IQ Battery, Franklin WH) may qualify as part of a broader clean energy project — confirm with a tax professional before assuming credit eligibility. Some state utility programs offer limited generator rebates in storm-prone regions; Louisiana and Florida have offered periodic programs. For a full overview of which home improvement projects qualify for federal credits, see our home improvement tax credits guide.

Annual Maintenance Costs

Standby generators require annual service to remain reliable: oil change, spark plug replacement (air-cooled units), air filter replacement, battery check, and coolant inspection on liquid-cooled units. Annual service contracts from generator dealers run $150–$350 per year. Generators perform automatic weekly exercise cycles (10–20 minutes at low load) to keep oil circulated and the engine ready — these are automatic and consume minimal fuel.

Budget $200–$400 per year for maintenance. Over the generator's 25–30 year expected lifespan, the full lifecycle cost of a $12,000 installed generator is approximately $17,000–$22,000 — roughly $680–$880 per year amortized.

Smart Home Integration

Modern Generac and Kohler generators connect to mobile apps (Generac Mobile Link, Kohler OnCue) that monitor utility power status, fuel level, exercise cycle completion, and fault alerts remotely. This makes generator ownership significantly less anxiety-inducing during travel and storm season. The integration fits naturally into broader home automation investments. For context on how a generator fits within a larger smart home infrastructure project, see our smart home upgrades cost guide.

To find licensed electrical contractors and remodeling contractors with standby generator installation experience in your area, browse our directory by city or search for home remodelers near you with generator installation credentials.

Frequently Asked Questions

How much does a whole-house generator cost installed?: A whole-house standby generator costs $7,000–$25,000 installed, including the unit, automatic transfer switch, fuel connection, concrete pad, and electrical work. Most homeowners with a 2,000–3,000 sq ft home land at $10,000–$16,000 for a 14–22 kW unit. Larger homes, complex electrical panels, or propane sites with tank installation push toward the top of the range.
What size generator do I need for a whole house?: A 2,000 sq ft home with central HVAC, a refrigerator, lights, and standard appliances needs roughly 10–14 kW to run everything simultaneously. A 3,000 sq ft home with a heat pump, well pump, or EV charger typically needs 18–22 kW. Add the running wattage of your HVAC system (typically 3,500–7,000W for central AC) plus 5,000W for essential circuits to estimate minimum capacity.
What is the difference between a standby generator and a portable generator?: A standby generator is permanently installed outdoors, connected to your home's electrical panel via an automatic transfer switch, and starts within seconds of a power outage with no homeowner action required. A portable generator runs on gasoline from portable tanks and must be connected manually. Standby generators cost 5–10 times more but provide seamless, automatic whole-home backup.
Natural gas vs. propane for a whole-house generator: which is better?: Natural gas is preferred where a gas line is available — it requires no fuel storage, has unlimited supply during most outages, and costs less per kWh than propane. Propane requires a 250–1,000 gallon on-site tank but is available in areas without natural gas service. Diesel offers high energy density but poses storage, degradation, and regulatory complications that make it uncommon for residential use.
Do I need a permit to install a whole-house generator?: Yes. Almost all jurisdictions require electrical and gas permits for standby generator installation. The electrical permit covers the transfer switch and panel connection; the gas permit covers the fuel line connection. Most jurisdictions also require setback review — typically 5 feet from windows and doors, 18 inches from combustibles. Permit costs run $100–$500 and are usually included in contractor quotes.