Whole-House Generator Costs
A permanently installed standby generator turns itself on within seconds of an outage and can run for days on natural gas or propane. That convenience comes with a real price tag, and the total depends heavily on how much of the house you want to keep running. Here is how the numbers break down in 2026.
The short version
- An installed air-cooled home standby generator typically runs $5,000 to $15,000 or more.
- That total usually includes the unit, an automatic transfer switch, and a mounting pad.
- Generator size (kW), fuel type, and the length of gas and electrical runs drive the price.
- Larger liquid-cooled units and long runs push the cost higher.
- This job needs a licensed electrician, often a gas fitter or plumber, plus permits and a utility notification.
Standby vs portable
A portable generator is the low-cost option: you roll it out, start it, and run extension cords or a manual inlet to a few essential loads. It is far cheaper up front but demands hands-on operation, refueling, and safe outdoor placement well away from the house every time the power goes out.
A standby generator is permanently installed outside on a pad, wired into your electrical system, and fed by natural gas or a propane tank. It starts automatically, needs no cords, and can carry far larger loads. This guide focuses on standby units, since those are the ones that involve real installation cost and licensed trades.
Sizing: whole home vs essential circuits
Generators are rated in kilowatts (kW), and sizing is the decision that most affects both price and how the system behaves during an outage. You are choosing between two philosophies.
- Essential circuits. A smaller unit powers a chosen set of critical loads — furnace or heat, refrigerator, well pump, some lights and outlets. It costs less and is right for many homes.
- Whole home. A larger unit backs up nearly everything, including central air conditioning and electric ranges. It costs more and often needs a bigger fuel supply.
- Load management. A middle path uses smart load-management devices to run a large home on a smaller generator by shedding heavy loads intelligently, which can lower the unit size you need.
The transfer switch
Every safe standby installation includes a transfer switch, which disconnects your home from the utility before the generator feeds power in. This is not optional — it protects utility line workers and prevents backfeeding the grid. An automatic transfer switch senses the outage and switches over on its own, while a manual switch requires you to flip it. Automatic switches cost more but deliver the hands-off experience most people want from a standby system.
What drives the price
- Generator size. Bigger kW ratings cost more, and the jump from air-cooled to liquid-cooled units is significant.
- Fuel type and supply. Natural gas taps your existing line if it has capacity; propane needs a tank. Either may require new gas piping.
- Gas and electrical runs. The farther the unit sits from the meter and the gas source, the more pipe and wire — a major cost variable.
- Pad and site work. A concrete or composite pad, plus any grading or clearance work, adds to the base.
- Permits and inspection. Standby generators are permitted work and usually require a utility notification as well.
Typical 2026 installed cost by size
These are broad, installed-cost ranges for air-cooled home standby systems including a transfer switch and pad. Liquid-cooled and long-run installs run higher.
| System | Typical installed range | Backs up |
|---|---|---|
| Small standby (around 10 to 14 kW) | $5,000 to $9,000 | Essential circuits |
| Mid standby (around 16 to 20 kW) | $8,000 to $13,000 | Most of a typical home |
| Large air-cooled (around 22 to 26 kW) | $11,000 to $16,000+ | Whole home incl. central AC |
| Liquid-cooled or long runs | $15,000 and up | Large homes, distant placement |
| Automatic transfer switch (in above) | included | Hands-off switchover |
Why it takes licensed pros
A standby generator sits at the intersection of two regulated trades. The electrical side — the transfer switch, the connection to your panel, and the wiring — must be done by a licensed electrician. The fuel side — tapping a natural gas line or setting up propane — often requires a licensed gas fitter or plumber. The work is permitted, inspected, and typically requires notifying your utility. This is not a project to piece together informally; a wrong transfer-switch connection is dangerous to you and to line workers.
Pro tip — get a load assessment before you pick a size
The most common regret is buying too small or too large. Have an electrician assess your actual loads and talk through whether you want whole-home coverage or essential circuits before you settle on a kW rating. Right-sizing at the quoting stage is far cheaper than discovering the unit cannot carry your air conditioning after it is installed.
FAQ
What size generator do I need?
It depends on whether you want to back up essential circuits or the whole home, and on big loads like central air and electric heat. An electrician can run a load assessment to recommend a kW rating. Load-management devices can sometimes let a smaller unit cover a larger home.
Natural gas or propane?
Natural gas is convenient if your line has spare capacity, since it never needs refilling. Propane suits homes without gas service but requires a tank you keep filled. Your installers will check whether your gas line can supply the generator or whether new piping is needed.
Do I need an automatic transfer switch?
A transfer switch of some kind is required for safety. Automatic switches sense the outage and switch over on their own, which is what makes a standby system hands-off. Manual switches cost less but require you to operate them each time.
What does annual maintenance cost?
Standby generators need periodic service — oil, filters, and a run check — typically a few hundred dollars a year depending on the unit and provider. Many owners buy a maintenance plan. Skipping service is the most common reason a generator fails to start when it is finally needed.
General information for homeowners — not a substitute for a licensed electrician. Electrical work can be dangerous and is regulated by code; always hire a licensed pro and pull required permits. Costs and codes vary by location.
