Standby Generator Installation Cost Calculator

A complete standby generator system typically costs $8,000 to $18,000, with most homeowners paying around $10,000 to $15,000 for a whole-home unit including the generator, the automatic transfer switch, and the electrical and fuel connections. On a per-kilowatt basis, that's about $750 to $900 per kW installed. A smaller essential-circuits system (10-14 kW) can run $6,000 to $10,000, while a large whole-home unit (22-26 kW) with a service upgrade, a propane tank, and a long fuel/electrical run can exceed $20,000 to $25,000. The main cost drivers are the generator's capacity in kilowatts (the biggest factor), the fuel type (natural gas ~$750/kW, propane ~$800, diesel ~$900), the transfer switch (whole-home automatic, load-managed, or essential-circuits), the electrical work (a simple panel tie-in versus a full service upgrade), and the distance from the panel and fuel source to the generator pad. A ~$4,000 job minimum applies. Add-ons like a concrete pad, a propane tank, permits, and monitoring add to the total. Enter your capacity and options above for a localized estimate.

It depends on how much of your home you want to power during an outage. A whole-home generator that runs everything — including large loads like central AC, an electric range, and an electric water heater — typically needs 18 to 26 kW for an average home (a 22 kW unit is a very common whole-home size), with larger or heavy-electric homes needing 26 to 48 kW. An essential/managed approach that powers just the critical items — refrigerator, furnace or heat, some lights and outlets, a sump or well pump — can work with a smaller 10 to 14 kW unit, often paired with load management that sheds or prioritizes circuits so the smaller generator handles peak demand. A professional performs a load calculation: they total your running loads plus the motor-starting surges (AC compressors and pumps draw extra on startup), then size the generator with headroom. Central AC is usually the biggest single factor, and electric heat or an EV charger add significant load. Don't guess — undersizing means the generator can't start the AC or overloads, while oversizing wastes money. Enter your target kW above; a pro assessment nails the exact size.

For most homes, natural gas is the best choice if you have a utility gas line: it provides an unlimited, continuous supply so the generator runs indefinitely with no refueling, it's convenient (no tank to store or fill), clean-burning, and typically the cheapest fuel. Its only real limits are that it needs a gas line (not available in many rural areas) and depends on the gas utility staying on. Propane (LP) is the best option for homes without natural gas: it burns clean, stores indefinitely without degrading (unlike diesel or gasoline, which matters for standby use), and is slightly more energy-dense than natural gas — the trade-off is a finite on-site tank that can run out in a very long outage and needs refilling. Diesel is mainly for very large loads or commercial use: it's power-dense and durable but requires a fuel tank, refueling, and fuel maintenance (diesel degrades over time), and it's louder and less clean, so it's uncommon for typical homes. Bottom line: natural gas if you have it, propane if you don't, diesel for large or commercial loads. This calculator includes all three, with natural gas as the lowest per-kW rate.

An automatic transfer switch (ATS) is the device that safely and automatically switches your home's electrical supply between the utility grid and the generator, and it's an essential, code-required part of any standby system. It constantly monitors the utility power; when it detects an outage, it signals the generator to start, and once the generator is running (within about 10-30 seconds) it disconnects the home from the grid and connects it to generator power — then reverses the process and shuts the generator down when utility power returns and stabilizes. All of this happens without you doing anything, even if you're not home, which is what makes a standby generator 'automatic.' Critically, the ATS isolates your home from the grid while on generator power, preventing dangerous backfeed — generator power feeding back into the utility lines — that could electrocute utility workers repairing them and damage equipment. It also ensures the grid and generator are never connected at once, protecting the generator. A transfer switch is required by electrical code; you can't safely connect a generator to your home's wiring without one. This calculator includes whole-home, load-managed, and essential-circuit switch options.

Yes on both counts — standby generator installation almost always requires permits (electrical, usually gas/fuel, and often building/mechanical) and must be done by licensed professionals. This is not a DIY project. The work involves high-voltage connections to your electrical panel, the safety-critical transfer switch that prevents deadly backfeed, and fuel connections (a natural gas tie-in or a propane tank and line) where a leak risks fire, explosion, or carbon monoxide — so it requires a licensed electrician and, for the fuel, a qualified gas fitter or plumber. Permits ensure the installation meets electrical and gas codes and passes inspection, which matters for safety, insurance, and resale; skipping them risks all three. The generator also must be placed to code — proper clearances from the house, windows, combustibles, and property lines. On top of that, professional installation (and often authorized-dealer commissioning) is typically required for the manufacturer's warranty to be valid. The right approach is to hire a qualified installer — often an authorized generator dealer — who pulls the permits, sizes and installs the system to code, handles the fuel and electrical work, and commissions it. This calculator includes a permit add-on and estimates professional installation.

Beyond the generator unit itself (priced per kW by fuel), three installation factors round out the estimate. The transfer switch: a whole-home automatic switch that powers the entire panel adds about $2,000, a load-managed switch about $1,400, an essential-circuits switch about $900, or you may reuse an existing compatible switch for no added cost. The electrical work: a simple panel tie-in adds about $600, a moderate job with a subpanel or some rewiring about $1,200, and a complex job requiring an electrical service upgrade about $2,200 (needed when your existing service can't handle the addition). The distance from the electrical panel and fuel source to the generator pad: an adjacent location adds nothing, a moderate run adds about $500, and a long run needing trenching for the wiring and fuel line adds about $1,100. These stack on top of the per-kW generator cost, which is why placement near your panel and meter — and reusing a switch or keeping electrical simple where possible — meaningfully lowers the total. This calculator lets you set each of these.

For many homeowners, yes — a standby generator is worth it for the reliability and peace of mind of automatic backup power, and it can add resale value. It shines if you experience frequent or long outages (storms, grid instability, ice storms), if you rely on power for medical equipment, a home office, a sump pump (to prevent basement flooding), a well pump, or refrigerated food and medication, or if you simply want the whole home to keep running seamlessly during an outage. Unlike a portable generator, a standby unit starts and transfers automatically within seconds — you don't have to be home, haul fuel, or run cords — and with natural gas or a large propane tank it can run for days. On value, a whole-home standby generator is a desirable feature that buyers notice, particularly in outage-prone regions, and it can modestly boost resale appeal, though it won't fully return its cost like some renovations. Weigh your outage frequency, what you need to keep running, and whether the convenience and security justify the investment. If outages are rare and brief, a smaller essential-circuits system or a portable unit may make more sense.

The hands-on installation is usually 1 to 3 days, but the overall project — from order to a running system — often spans 4 to 8 weeks once you factor in unit lead times, permits, and any fuel or electrical prep. A standard whole-home install with a nearby natural gas line and a straightforward electrical tie-in is often done in 1 to 2 days: placing the generator on its pad, connecting the fuel, installing the transfer switch, wiring it to the panel, and commissioning and testing it. More involved jobs take 2 to 3+ days — a propane tank installation, a long fuel or electrical run needing trenching, a service upgrade, or a poured concrete pad that must cure. The longer part of the timeline is usually the unit lead time (from in-stock to several weeks depending on size and brand) plus permitting (days to weeks depending on the locality) and scheduling. After installation, electrical and gas inspections are scheduled and the system is commissioned. Because the full project can take several weeks, it's wise to plan ahead — ideally before storm season — even though the on-site work itself is quick.