How Much Does a Whole House Generator Cost to Install?

Updated on June 28, 2026 | Written by Alec Pow
This article was researched using 12 sources. See our methodology and corrections policy.

A whole house generator usually costs $6,000 to $11,000 installed for a standard home standby system, while larger or more complicated projects can reach $13,500 to $21,000+. A smaller portable generator costs much less, often $500 to $2,500 for the unit alone, but it is not the same as a permanently installed standby generator with an automatic transfer switch, gas connection, concrete pad, permits, and professional electrical work.

A whole house generator is usually a permanent standby unit from brands such as Generac, Kohler, Briggs & Stratton, or Cummins. It sits outside the home, runs on natural gas or liquid propane, and connects to the electrical panel through a transfer switch. The price changes with generator size, the circuits you want backed up, fuel line distance, panel work, local permits, and whether you choose essential-circuit backup or near whole-home coverage.

Article Highlights

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• Most installed standby generator systems cost $6,000 to $11,000 (at $30 per hour, earning that amount would take about 5 to 9.2 full-time workweeks, before taxes), with large or difficult jobs reaching $13,500 to $21,000+.
• The generator unit often costs $3,000 to $6,000 before labor, wiring, fuel connection, permits, and site work.
• Installation labor and project work often add $3,000 to $5,000, and long runs or large systems can add more.
• A portable generator setup can cost $900 to $4,000 when connected safely to selected circuits, but it is not a whole house standby system.
• Gas line work, panel upgrades, concrete pads, permits, transfer switches, and annual maintenance are the most common hidden costs.
• A move from a $6,000 essential backup setup to an $11,000 standby setup adds $5,000, or about 83% more.

How Much Does a Whole House Generator Cost?

HomeAdvisor lists whole-house generator installation at $1,516 to $8,811 (about 1.3 to 7.3 full-time workweeks at $30 per hour), with many homeowners paying around $5,161, according to its generator installation cost guide. That lower range can include smaller backup setups, so homeowners pricing a true standby generator with automatic startup should expect the quote to climb when fuel, transfer switch, panel, and site work are included.

Angi places whole-house generator installation between $350 and $13,500, with an average near $5,161, and notes that capacity, fuel type, concrete pad, transfer switch, permits, and panel work all affect the final bill in its whole-house generator cost data. For larger homes, long fuel runs, or higher-capacity standby systems, Angi also notes that projects can move past the common range.

The Home Depot’s installation cost guide puts generator installation at $5,000 to $12,500 based on unit size and project needs, which fits the price band many homeowners see for a professionally installed standby system through a retailer or local installer using its generator installation service.

Generator setup	Typical cost	Best fit
Portable generator, not hard-wired	$500 to $2,500	Temporary power for refrigerators, lights, chargers, and a few plug-in loads
Portable generator with manual transfer switch	$900 to $4,000	Selected circuits such as furnace, sump pump, refrigerator, internet, and lighting
Essential-circuit standby generator	$6,000 to $11,000	Automatic backup for important circuits without powering every appliance
Larger whole-home standby generator	$10,000 to $16,000+	More HVAC capacity, larger panels, more circuits, and higher electrical loads
Complex installation or large property	$13,500 to $21,000+	Long gas or electrical runs, trenching, panel upgrades, propane tank work, or multiple load demands

Standby vs Portable Generator Costs

A standby generator is the costlier option because it is permanently installed outside the house, wired into the home electrical system, connected to natural gas or propane, and paired with a transfer switch. It can start automatically during an outage, then shut down after utility power returns.

A portable generator is cheaper because it is a movable engine-driven unit. It can power appliances through heavy-duty cords or selected circuits through a properly installed manual transfer switch, but it is not a whole house system. A safe portable setup can still become expensive once you add a transfer switch, inlet box, electrician labor, weather-rated cords, and carbon monoxide safety equipment.

The difference is easiest to see in the math. A $2,500 (about 2.1 full-time workweeks at $30 per hour) portable generator plus a $1,300 transfer switch setup becomes a $3,800 project, and the switch portion alone equals 52% of the generator price. That is still below many standby systems, but it does not provide the same automatic backup experience.

Generator Size, Home Load

Generator size is measured in kilowatts, or kW. A smaller home backing up the basics may need far less power than a large house with central air, electric heat, an electric water heater, a well pump, an EV charger, a second refrigerator, or medical equipment. Generac’s standby generator finder separates whole-home backup from selected-circuit backup because those are different load profiles.

Kohler says smaller homes with limited backup needs may require 10 to 14 kW, while larger homes or homes with multiple HVAC systems may need 20 kW or more in its home generator sizing guidance. That is why the old rule of choosing a generator only by square footage can mislead homeowners. Two 2,000-square-foot houses can need different systems if one has gas heat and the other relies on electric heat pumps, a well pump, and a large central air conditioner.

Buying extra capacity can be expensive, but undersizing the generator can also cause problems. If the generator cannot handle startup loads from motors, pumps, and compressors, the system may shed loads, trip, or fail to power the equipment the homeowner expected to use during an outage.

What Is Included

The generator unit is only one part of the quote. HomeGuide puts whole house generators at $3,000 to $6,000 for the unit alone and $6,000 to $11,000 installed, with labor commonly adding $3,000 to $5,000 and longer or larger installations costing more in its whole house generator cost guide.

A complete quote can include the standby generator, automatic transfer switch, electrical wiring, conduit, load management modules, concrete or composite pad, gas line, regulator work, battery, startup testing, permits, inspections, and cleanup. If the generator is far from the gas meter or electrical panel, trenching and longer conduit runs can raise both labor and materials.

Electrician labor is a real part of the installed cost. HomeGuide lists electrician hourly rates at $50 to $130 on average, with a first-hour or service call fee often at $100 to $200, in its electrician cost data. Generator work is not a small outlet repair, so the bill reflects planning, panel work, load calculations, transfer switch wiring, testing, and inspection coordination.

Transfer Switch, Panel Work

A transfer switch is not just an upgrade. It is the device that separates generator power from utility power, protecting the house, the generator, neighbors, and utility line crews. OSHA warns that a generator should not be attached directly to a building electrical system unless a qualified electrician has installed it with a transfer switch, according to its portable generator safety guidance.

An automatic transfer switch is common with standby generators. It senses the outage, starts the generator, shifts the home to generator power, and then transfers the home back to utility power when the grid returns. A manual transfer switch is more common with portable generators and selected circuits, but it still needs correct installation.

Panel upgrades or load management can add to the project. A homeowner who wants to run two air conditioners, an electric oven, a dryer, a well pump, and an EV charger may need a larger generator or a system that sheds some loads during an outage. That is often cheaper than buying a much larger generator just to run every appliance at once.

Natural Gas, Propane, Diesel

Most residential standby generators run on natural gas or liquid propane. Natural gas is convenient when the home already has utility gas service, but the installer still needs to confirm the gas meter, regulator, and pipe sizing can handle the generator. Propane works well where natural gas is unavailable, but it may require a larger tank and refills before long outages.

Gas line installation for a generator can cost $400 to $1,500+, and gas line work can also be priced at $15 to $50+ per linear foot when long runs or difficult access are involved, according to HomeGuide’s gas line installation cost data. Adding a $1,500 gas line to an $8,500 generator project raises the total to $10,000, an increase of about 18%.

Propane budgeting should not rely on an old national price range. The U.S. Energy Information Administration collects weekly residential propane price data during the October through March heating season, then limits propane price updates outside that season, as shown in its propane price update. Local delivery fees, tank ownership, minimum delivery amounts, winter demand, and emergency refills can matter as much as the posted per-gallon number.

Permits, Placement, and Safety

Whole house generator installations can require electrical, plumbing, mechanical, and building permits. The exact requirement depends on the city, county, utility, fuel type, and whether the work changes the gas line or electrical panel. Permit and inspection fees are often small compared with the generator itself, but skipping them can create resale, insurance, and safety problems.

Placement is not just about convenience. A fuel-burning generator must be installed with proper outdoor clearances, exhaust direction, service access, and separation from windows, doors, vents, gas meters, and property lines. The old idea of putting a generator in a garage because the floor is already concrete is not a safe cost-saving shortcut.

The U.S. Consumer Product Safety Commission says portable generators should never be used inside homes, garages, basements, crawlspaces, sheds, or other enclosed areas, and should be operated outdoors at least 20 feet from homes and buildings with exhaust directed away from openings in its generator CO warning. Permanent standby generator placement should follow the manufacturer manual, local code, and the installer’s approved plan.

For nearby electrical projects, ThePricer also covers the cost of GenerLink, burying power lines, and GFCI outlet installation.

Three Budget Examples

A basic emergency backup setup might cost $3,000 to $4,500 if the homeowner uses a portable generator, a manual transfer switch, an inlet box, and selected circuits only. This can keep a refrigerator, furnace blower, sump pump, lights, and internet running, but it requires manual setup and safe outdoor operation during every outage.

A standard standby system for selected circuits often lands around $7,000 to $11,000. This type of quote may include a 10 to 14 kW standby generator, automatic transfer switch, short gas line, pad, electrical work, permit, and startup testing. It fits homes that want automatic backup but do not need every circuit powered.

A larger whole-home setup can reach $12,000 to $18,000+ when the home needs 20 kW or more, has multiple HVAC loads, requires a longer gas line, needs panel upgrades, or uses load management modules. A rural property with a long trench, propane tank work, and difficult access can move past that range.

Here is a worked total: start with a $6,500 standby generator package, add $1,500 for gas line work, $800 for panel and load management work, $400 for a pad, and $300 for permits and inspection. The installed total becomes $9,500. If the same home needs a larger unit and longer trenching, the quote can cross $12,000 before any optional monitoring or extended service plan.

Maintenance and Operating

A standby generator is not a one-time cost. It needs oil changes, filter changes, battery checks, exercise testing, transfer switch testing, inspection, and service after heavy use. HomeGuide lists annual generator maintenance plans at $200 to $650, with repairs ranging from $50 for small issues to $2,500 for major problems in its generator maintenance cost guide.

Fuel use depends on generator size, load, fuel type, and outage length. A generator running only a few essentials uses less fuel than one carrying central air, electric cooking, laundry, pumps, and multiple refrigerators. During a long outage, managing loads can reduce fuel use and help the generator run more reliably.

Battery replacement, monitoring subscriptions, service agreements, and emergency service calls can add to ownership costs. A $300 annual maintenance visit over 10 years adds $3,000 to the lifetime budget, before fuel or repair costs. That amount is worth including when comparing a standby system with a lower-cost portable setup.

Answers to Common Questions

How much does a 20 kW whole house generator cost installed?

A 20 kW standby generator often falls around $8,000 to $16,000+ installed, depending on brand, transfer switch, fuel line, panel work, permits, and site access. The generator unit is only part of the total.

Is a portable generator a whole house generator?

No. A portable generator can back up selected appliances or circuits, but it is not the same as a permanent standby generator. A portable unit also requires safe outdoor placement and either direct appliance cords or a properly installed manual transfer switch.

Can I install a whole house generator myself?

A portable generator can be used by a homeowner when it is operated safely, but a hard-wired standby generator should be installed by licensed electrical and fuel professionals. The work involves panel wiring, transfer switch installation, gas or propane connection, permits, testing, and code compliance.

Does a whole house generator need a concrete pad?

Many standby generators need a stable pad or approved base. Some installs use a concrete pad, while others use a manufacturer-approved composite pad. The right option depends on generator size, soil, drainage, local code, and the manufacturer’s installation manual.

Is natural gas or propane cheaper for a standby generator?

Natural gas is often more convenient if the home already has gas service, while propane is common in rural areas without gas utility lines. The cheaper option depends on local fuel prices, tank ownership, delivery fees, meter capacity, and how long the generator runs during outages.

Will a whole house generator run central air conditioning?

It can, but only if the generator is sized for the air conditioner’s running and startup load or uses load management. Large central air units, heat pumps, well pumps, and electric appliances can push the system toward a larger and more expensive generator.

How long does installation take?

The onsite work can take one to several days, but the full process may take longer because of quote visits, load calculations, permits, utility coordination, equipment delivery, inspection, and final startup testing.