Whole-House Generator Cost: What You'll Actually Pay in 2025
Whole-house standby generators cost $7,000–$20,000 installed. Learn what drives the price, how to size correctly, and what installers won't tell you upfront.
A whole-house standby generator is one of the few home improvements that pays for itself the first time you actually need it — and one of the few where a bad installation decision can kill you. This guide covers the real cost range, what drives it, and the questions you need to ask before signing anything.
What a Whole-House Generator Actually Costs
Most homeowners spend $10,000–$16,000 for a properly sized, code-compliant standby generator installed by a licensed electrician. The full range runs from roughly $7,000 on the low end (smaller homes, simpler installs, no gas line work) to $20,000 or more for large homes, complex electrical panels, or propane tank installations.
| Generator Size | Typical Home Size | Installed Cost Range |
|---|---|---|
| 10–13 kW | 1,000–1,500 sq ft | $7,000–$11,000 |
| 16–20 kW | 1,500–2,500 sq ft | $10,000–$15,000 |
| 22–26 kW | 2,500–3,500 sq ft | $13,000–$18,000 |
| 30–36 kW | 3,500+ sq ft | $16,000–$22,000+ |
These are installed costs — equipment plus labor, transfer switch, permits, and basic gas line hookup. Equipment-only pricing you see online is meaningfully lower, but installation typically runs $3,000–$6,000 on top of it.
What's Driving Your Specific Number
Generator Size (the Biggest Variable)
Getting the sizing wrong is the most expensive mistake you can make. Undersized generators drop voltage under load, damaging appliances. Oversized generators run "wet" (unloaded), fouling the engine with oil buildup over time.
Proper sizing requires a load calculation — adding up the starting wattage of every circuit you want to power, not just the running wattage. Air conditioning compressors draw 2–3x their running load on startup. That spike is what trips breakers and what an undersized generator can't handle.
A licensed electrician will do this calculation. Any installer who sizes by square footage alone without reviewing your electrical panel is cutting corners.
Transfer Switch Type
A manual transfer switch (cheaper, around $500–$1,500 installed) requires someone to physically flip switches when the power goes out. Fine for a vacation home. Inadequate for a primary residence where outages happen at 2 a.m.
An automatic transfer switch (ATS) detects the outage, waits 30 seconds for the utility to restore, then starts the generator and switches over — automatically, every time. This is what whole-house generators are actually sold with. Most systems transfer in 10–30 seconds. Budget $1,500–$3,000 for the ATS as part of a full installation.
Fuel Type
Natural gas is the preferred fuel for most whole-house installations — no storage, no deliveries, no fuel degradation, lower cost per kWh. The connection fee and gas line extension depends entirely on how far the generator sits from your existing line and your local utility's requirements.
Propane is the fallback when natural gas isn't available. You'll pay for tank rental or purchase (a 250-gallon tank runs $400–$800 to purchase; $50–$150/year to rent) plus delivery contracts. Propane also has lower BTU density than natural gas, meaning you'll burn through it faster for the same output.
Diesel generators are common in commercial applications but rare for residential standby. Higher upfront cost, fuel storage requirements, and maintenance demands don't make sense for most homeowners.
Electrical Panel Condition
Older panels (60 or 100 amp service, fuse boxes, Federal Pacific or Zinsco panels) often need upgrades before a generator install can proceed. A panel upgrade runs $2,000–$4,000 depending on amperage and local labor. Your installer should flag this in the initial assessment. If they don't mention it and your panel is older, ask directly.
Permits and Inspection
Every legitimate generator installation requires permits — electrical and often mechanical. Permit fees vary by municipality but typically run $200–$600. Any installer who offers to skip permits is offering to create a liability problem for you: generator work done without permits can void homeowner's insurance coverage and create sale issues when you eventually list the property.
Brands Worth Knowing
Generac is the dominant residential standby brand — roughly 70% market share. Widely installed, parts are available everywhere, most electricians are familiar with them. Their Evolution controller is well-regarded.
Kohler is the premium alternative. Better build quality on larger units, more robust customer service reputation. Costs 10–20% more than comparable Generac models, typically worth it on larger installs.
Briggs and Stratton and Cummins have solid standby lines, though dealer networks are thinner. Champion and other budget brands are fine for portable generators; for permanent standby installs, stick with the established players.
Annual Maintenance Costs
This is where people get surprised. Standby generators require annual service — oil change, filter replacement, spark plugs, load bank test, battery check. Budget $150–$300 per year for professional annual maintenance. Most manufacturers require documented annual service to maintain warranty coverage.
The generator also runs a weekly self-test (typically 12 minutes) to keep itself ready. This uses a small amount of fuel and keeps the battery charged.
What the Quote Should Include
A complete generator installation quote covers: equipment with warranty, automatic transfer switch, concrete or composite pad, all conduit and wiring to the panel, gas line connection (or note of what gas work is separate), permit fees, and one year of labor warranty. If the quote line-itemizes "gas line work" as an extra, get clarity on scope and cost before signing.
Get three quotes. Generator installation pricing varies significantly by region and by how busy the installer is. The difference between quotes on the same equipment can be $2,000–$4,000.
The One Thing That Kills Deals Post-Install
HOA approval. Many HOAs restrict generator placement, require screening, or prohibit certain fuel types. Get written HOA approval before you sign with an installer — not after. Retrofitting a generator location for HOA compliance, or removing and reinstalling one, is an expensive and entirely avoidable problem.
Have a generator install coming up and want a licensed contractor's eye on the quote? Schneider Construction and Development offers remote bid review available nationwide — send your quotes to hello@schneidercondev.com and get a review within 48 hours.
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Written by BlueprintKit
BlueprintKit publishes expert construction and renovation content based on real project experience. Every guide is reviewed by a licensed general contractor.