Whole House Generator Cost Calculator
Size the right standby generator for your home, then estimate the full installed price — equipment, transfer switch, fuel plumbing, pad, permits and labor — plus yearly ownership cost and an honest standby-vs-portable comparison.
Size my generator
Running watts + the single largest motor-starting surge, with the 80% continuous-loading rule and ~3%/1,000 ft altitude derate.
- Total running load
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- Peak (surge) load
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- Capacity needed
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Installed cost estimator
Planning estimates from published 2026 component ranges — not a quote. Get three itemized bids.
Ownership cost & standby vs portable
Yearly cost = maintenance plan + exercise fuel + outage fuel. Compare the 10-year total cost of ownership (TCO) against a 7.5 kW portable + manual transfer switch.
Annual ownership
10-year total cost of ownership
- Standby (installed + 10 yrs)
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- Portable 7.5 kW (installed + 10 yrs)
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- Standby premium over 10 years
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How whole-house generator pricing works
A whole-house generator — also called a standby generator — is permanently wired into your home's electrical panel and fueled by natural gas or propane. When the grid fails, an automatic transfer switch starts the unit and takes over your panel in seconds, with no extension cords and no refueling runs in a storm. The headline price you see online is almost never the full story: the generator unit itself is typically only roughly 40–60% of the finished project. The rest is the automatic transfer switch, licensed electrical labor, fuel plumbing (a gas line or a propane tank), a concrete pad, and permits with inspection. That is why two neighbors can buy the same 22 kW unit and pay totals thousands of dollars apart — the equipment is identical, but trenching distance, panel condition, and local labor rates are not.
Size drives the price more than brand does. Generator capacity is set by two numbers: the running watts of everything that will be on at once, plus the single largest motor-starting surge — a 3-ton air conditioner may run at 4,200 W but briefly demand over 12,000 W to start its compressor. This calculator adds both, then applies the industry 80% rule (a generator should not run flat-out for hours) and derates about 3% per 1,000 feet of elevation, since engines lose power at altitude. The result is rounded up to the nearest standard standby size: 7, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 30 kW and up. Buying one size too big wastes thousands on equipment and fuel; one size too small means the unit stalls when the AC kicks in. If you are between sizes, a smart transfer switch with load shedding can often let you drop down one size.
Fuel choice shapes both installation and running cost. Natural gas is the cheapest to live with: a typical gas-line run adds about $1,200 to the install, and a 22 kW unit burns roughly $55.44 of gas per 12-hour outage day at $1.50 per therm. Propane needs a tank — a 500-gallon tank plus line runs about $3,600 installed — and the same outage day costs roughly $126.72 in propane at $3.00 per gallon, because propane carries less energy per dollar. Propane's advantage is independence: it works where there is no gas service and stores indefinitely, but size the tank for several days, since delivery trucks do not run during major storms.
The biggest cost variable is your site. A simple install — panel and gas meter a few feet apart, easy pad location — can come in 20% under the typical figure; a complex one with 100+ feet of trenching, a long gas run, or difficult access can run 60% over. Regional labor multiplies everything again: the Northeast and West Coast commonly run 20–40% above the national average. Treat every number on this page as a planning estimate, then get three itemized quotes and compare them line by line — unit, transfer switch, electrical, fuel work, pad, permits. Any bid missing a line is a change order waiting to happen.
Typical installed cost by size (2026)
Value tier (Generac/Briggs-class), natural gas, typical site, national-average labor. Model planning estimates — your site moves you inside the range.
| Size | Equipment (value tier) | Installed, typical site | Planning range |
|---|---|---|---|
| 10 kW | $3,500 | $9,100 | $7,720 – $11,940 |
| 14 kW | $4,400 | $10,280 | $8,860 – $13,230 |
| 18 kW | $5,250 | $11,410 | $9,960 – $14,470 |
| 22 kW | $6,000 | $12,440 | $10,950 – $15,600 |
| 26 kW | $6,700 | $13,420 | $11,900 – $16,690 |
| 30 kW | $7,400 | $14,400 | $12,840 – $17,780 |
Worked examples
Example 1 — 2,400 sq ft home, 3-ton AC, natural gas
- General loads: 2,400 sq ft × 2.5 W = 6,000 W running.
- Air conditioner: 3 tons × 1,400 W = 4,200 W running; 3 × 4,200 W = 12,600 W starting (surge gap 8,400 W).
- Totals: 10,200 W running and 18,600 W surge → 19.06 kW needed after the 80% rule and altitude derate (800 ft).
- Round up to the nearest standard size: 20 kW.
- Installed cost: $5,600 + $2,000 + $2,100 + $1,200 + $650 + $350 = $11,900 (range $10,430–$15,010).
- Yearly ownership: $450 maintenance + $60 exercise fuel + 5 outage days × $50.40 = $762.00/year.
Example 2 — 4,200 sq ft home, 4-ton AC + well pump, propane, premium tier, smart transfer switch, complex site (Northeast)
- Loads total 17,100 W running with a 28,300 W surge → 29.36 kW needed → 30 kW standby.
- Premium-tier equipment costs more up front ($9,050 for the 30 kW unit vs. $7,400 value-tier).
- Installed: $9,050 + $3,300 + $4,900 + $3,600 + $1,100 + $550 = $22,500 (range $19,100–$22,500).
- Propane at $3.00/gal makes outage days pricey: about $172.80 per 12-hour day — the trade-off for having no gas service.
Tips to avoid overpaying
- Get three itemized quotes and compare them line by line — unit, transfer switch, electrical, fuel work, pad, permits. The cheapest lump sum often just hides the most lines.
- Do not oversize. Each extra kilowatt costs roughly $175–$250 in equipment alone on a value-tier unit, plus more fuel every outage.
- Ask whether a smart switch with load shedding lets you drop one generator size — the switch premium is often smaller than the equipment savings.
- On natural gas, have the installer verify your gas meter's capacity. An undersized meter is a common $500–$1,500 surprise.
- Budget the maintenance plan from day one. Most failure-to-start calls trace back to skipped service, not to the brand.
- Schedule in spring if you can — installers commonly discount off-season work versus post-storm panic buying.
Frequently asked questions
How much does a whole-house generator cost installed?
Most residential standby projects land between $8,000 and $13,000 fully installed for typical 7–24 kW sites. In this calculator's model, a 22 kW value-tier (Generac-class) unit on natural gas with a typical site runs about $12,440 installed (planning range $10,950–$15,600), and a 14 kW essentials system about $10,280. The generator itself is roughly 40–60% of the project; the rest is the transfer switch, electrical labor, fuel plumbing, concrete pad, and permits.
What size whole-house generator do I need?
Size from your loads, not just square footage: add up running watts, then add the single largest motor-starting surge, and keep continuous load under about 80% of the rating. As a worked example, a 2,400 sq ft home with a 3-ton central AC needs about 19.06 kW (10,200 W running, 18,600 W surge), which rounds up to the standard 20 kW size. Rule of thumb: 7–10 kW covers essentials, 14–18 kW adds a small AC or well pump, and 22–26 kW covers a typical 2,000–3,000 sq ft whole home.
How much does a Generac 22 kW generator cost installed?
A 22 kW Generac Guardian-class unit is the most common residential size. Equipment alone typically lists around $5,300 (budget/Champion-class) to $7,300 (premium/Kohler-class), with the value tier near $6,000. Installed with an automatic transfer switch, gas line, pad, permits, and labor on a typical site, expect roughly $12,440 all-in (range $10,950–$15,600 depending on site complexity). Always compare itemized quotes, because gas-line length and panel work swing the total by thousands.
What is included in a whole-house generator installation?
A complete quote should itemize: the generator unit, the automatic transfer switch, electrical labor and wiring, the fuel system (natural-gas line or propane tank plus line), the concrete or composite pad, and permits/inspection. For the 20 kW example in this guide the model breaks down as $5,600 unit + $2,000 transfer switch + $2,100 electrical labor + $1,200 gas line + $650 pad + $350 permits = $11,900. If any line is missing from a bid, ask — that is where surprise change-orders come from.
Is natural gas or propane cheaper for a whole-house generator?
Natural gas is usually cheaper both to install (a gas line runs about $1,200 on a typical site vs. $3,600 for a 500-gallon propane tank plus line) and to run. A 22 kW unit costs about $55.44 per 12-hour outage day on natural gas versus about $126.72 on propane at typical 2026 fuel prices. Propane makes sense where there is no gas service; size the tank for at least several days of outage, since deliveries stop in major storms.
How much does it cost to maintain a whole-house generator per year?
Budget about $450 per year for a value-tier annual service plan (oil, filters, spark plugs, battery check, load test), plus roughly $60 in fuel for the weekly exercise cycle. With 5 outage days a year on natural gas, total yearly ownership is about $787.20 ($1,143.60 on propane). Skipping maintenance is the most common cause of failure-to-start.
How long does a whole-house generator last?
Air-cooled standby units are typically rated for 2,000–3,000 operating hours. In standby duty — a few dozen hours of outages plus weekly exercise per year — that translates to roughly 20–25 years of service for quality units, with budget units closer to 12–15 years. Longevity depends far more on regular maintenance and proper sizing (chronically overloaded units die young) than on brand alone.
Can I install a whole-house generator myself?
No — this is not a DIY project. Installation requires a licensed electrician (240 V service-entrance work), a gas fitter for the fuel line, permits and inspections, and manufacturer-authorized commissioning. DIY installation voids the warranty, can violate local code, and risks carbon-monoxide or backfeed hazards. Get at least three itemized quotes from certified installers.
Will a whole-house generator increase my home value?
It is widely cited as a selling feature in outage-prone areas, but there is no guaranteed dollar ROI — appraisers treat it as a home improvement with variable payback. Treat the purchase as resilience and convenience spending, not an investment: the honest math in this calculator's compare tab shows a standby costs about $14,130 more than a portable setup over 10 years. Buy it for automatic whole-home coverage, not for resale profit.
How loud is a whole-house standby generator?
Modern air-cooled standby units typically run 60–70 dBA measured at 23 feet — about conversational level to a vacuum cleaner, and noticeably quieter than an open-frame portable. Premium units with better enclosures sit at the low end. Codes and manufacturers require clearances (commonly 5 ft from doors/windows and 18 in from walls), so placement affects both noise at the bedroom window and the install price.
Do I need an automatic transfer switch?
Yes — a standby generator requires one. It detects the outage, starts the generator, and switches your panel over in about 10–30 seconds, then switches back when utility power returns. A standard 200 A whole-house switch adds about $2,000 installed for a 20 kW system in this model; smart switches with load shedding cost more but can let you buy one size smaller generator, often saving more than the switch premium.
Is a standby generator cheaper than a portable in the long run?
No. A 7.5 kW portable with a manual transfer switch installs for about $2,500 versus $11,900 for the 20 kW standby example here, and over 10 years with 5 outage days per year the standby costs about $14,130 more all-in ($19,520 vs $5,390). The standby premium buys automation — no dragging a unit out in a storm, no extension cords, whole-home coverage — not fuel savings.
Sizing a portable instead?
This tool prices permanently installed standby generators. If you are sizing a portable unit from an appliance list, use our generator wattage calculator — it does running-vs-starting-watts math for portables.
Free tool by NRTechStudio