Whole House Generator Cost Calculator
Use this free whole house generator cost calculator to estimate your total installed cost based on generator type, size, fuel, and site conditions. Whether you’re considering a budget-friendly portable setup or a fully automatic standby system, simply select your options to get an instant cost range.
14–16 kW is the most common whole-home size, covering a small-to-medium home plus one central AC · A standby unit's automatic transfer switch is included in its installed price · Portable generators run on gasoline, not the fuel type selected above
Estimates based on 2026 US average pricing from Angi, HomeGuide, and ProjectCostPro. Actual costs vary significantly by region, home electrical load, and site conditions. Always get 3 quotes from licensed installers.
Understanding the Calculator Inputs
Generator cost spans one of the widest ranges of any project on this site — from $1,500 for a portable setup to $38,000+ for a large liquid-cooled standby system. Generator type and size explain most of that spread.
Generator Type & Size — The Core Decision
A portable generator with a manual transfer switch (or interlock kit) is the budget option — you roll it out, fuel it, and manually switch over during an outage. It's cheaper but requires you to be present and willing to manage it. A standby generator is permanently installed, runs on natural gas or propane, and starts automatically within seconds of an outage via an automatic transfer switch wired into your panel — no manual intervention needed. Standby size in kilowatts (kW) determines how much of your home it can power; larger homes with central AC need more capacity.
Fuel Type
Most standby generators run on natural gas (if you already have gas service) or propane. If you don't have an existing propane tank, one needs to be installed — a real, separate cost. Portable generators typically run on gasoline rather than piped fuel, so the fuel type selector mainly matters for standby units.
Connecting a generator directly to your home's wiring without a proper transfer switch (automatic or manual) creates a serious risk of "back-feeding" — sending power back into the utility grid, which can seriously injure or kill utility workers repairing lines during an outage, and can also damage your generator once grid power returns. This is not a step to skip or DIY around, regardless of generator type.
3 Real-World Whole House Generator Examples
Example 1 — Portable Generator with Manual Transfer Switch
A homeowner wanting basic outage protection for essentials (fridge, some lights, a sump pump) without the cost of a permanent system, standard installation.
$1,500 – $4,500
Total:$1,500 – $4,500
Real-world note: This is the budget entry point and a reasonable choice for occasional, short outages where you're home and able to manage manual startup. It's not automatic, so it won't help if an outage happens while you're away.
Example 2 — Standard 14–16 kW Standby on Natural Gas
A typical small-to-medium home with existing natural gas service, installing the most common whole-house standby size, standard site conditions.
$10,000 – $18,000
Total:$10,000 – $18,000
Real-world note: This is the most common whole-house generator project and matches national averages closely. The installed price already includes the unit, automatic transfer switch, gas line hookup, pad, and permit — a complete standby install, not just the generator itself.
Example 3 — Large Standby on Propane, New Tank, Difficult Site
A large home needing 20–22 kW capacity for central AC and heavy loads, no existing propane service (new tank required), and a distant panel location requiring a longer gas and electrical run.
$12,000 – $22,000
Step 2 — New propane tank:$800 – $2,500
Step 3 — Difficult site surcharge:$1,000 – $3,000
Total:$13,800 – $27,500
Real-world note: This is exactly the kind of project that turns a $6,000-looking generator ad into a $14,000+ real installation — the transfer switch, pad, gas line, and site-specific work are where the real cost lives, not the generator unit's sticker price alone.
Portable vs. Standby Guide
| Type | Installed Cost | Automatic Start? | Best For |
|---|---|---|---|
| Portable + Manual Transfer Switch | $1,500–$4,500 | No | Occasional outages, budget-conscious, hands-on owners |
| Standby 8–10 kW | $8,000–$14,000 | Yes | Essentials only — heat, fridge, well, some outlets |
| Standby 14–16 kW | $10,000–$18,000 | Yes | Most homes — small-to-medium plus one central AC |
| Standby 20–22 kW | $12,000–$22,000 | Yes | Large home, central AC and heavier loads |
| Standby 30 kW+ (liquid-cooled) | $20,000–$38,000 | Yes | Very large or all-electric homes |
An interlock or manual switch for a portable setup runs a few hundred to about $2,000 — roughly 10–20% of a full standby install cost. The bulk of a standby generator's price comes from the unit itself, the gas line tie-in, the pad, and the automatic transfer switch's electrical labor, not the switch hardware alone.
Generator Sizing Guide
| Home Profile | Recommended Size | What It Powers |
|---|---|---|
| Small home, essentials only | 8–10 kW | Heat, refrigerator, well pump, sump pump, some outlets/lights |
| Small-to-medium home | 14–16 kW | Above, plus one central AC unit and most household circuits |
| Large home | 20–22 kW | Whole home including central AC and heavier appliance loads |
| Very large / all-electric home | 30 kW+ | Full home coverage including electric heat, multiple AC zones |
A licensed electrician sizes your generator based on an actual load calculation of your panel and the specific circuits you want backed up — this table is a starting reference, not a substitute for that assessment. Try our Electrical Load Calculator for a rough estimate of your own before that conversation.
Generator Cost Data Tables (2026)
Cost Breakdown for a Typical Standby Install
| Component | Share of Total |
|---|---|
| Generator unit | ~40% |
| Transfer switch & electrical labor | ~25% |
| Gas line hookup | ~15% |
| Pad & permits | ~10% |
| Sundry labor | ~10% |
Additional Cost Factors
| Factor | Cost |
|---|---|
| New propane tank | $800–$2,500 |
| Concrete/composite pad | $50–$75/sq ft |
| Automatic transfer switch (100–200A) | $1,800–$5,500 |
| Interlock kit (portable path) | $400–$900 |
| Manual transfer switch, 6–10 circuit | $1,000–$2,200 |
| Permit | $50–$200 |
| Annual maintenance (standby) | $200–$400 |
Common Estimation Mistakes
Budgeting Off the Generator Unit Price Alone
A 22kW generator advertised near $6,000 can become a $14,000+ complete project once the transfer switch, pad, gas line, electrical work, and permits are added. Always ask for an all-in installed quote, not just the equipment price.
Undersizing for Central AC
Central air conditioning has a significant starting (surge) load that catches some homeowners off guard when sizing a generator. If keeping AC running during an outage matters to you, confirm your chosen size accounts for that specific load, not just steady-state running wattage.
Skipping the Transfer Switch to Save Money
As covered in the safety callout above, connecting a generator without a proper transfer switch risks back-feeding the grid — a genuine safety hazard to utility workers, not just a code technicality. This is never the place to cut corners.
Not Checking Existing Fuel Service
Assuming you have adequate natural gas service or an existing propane tank without confirming can lead to a mid-project surprise. Confirm your actual fuel situation before comparing quotes, since a new propane tank is a real, separate cost.
Ignoring Ongoing Maintenance in the Decision
A standby generator that isn't serviced annually may not start reliably when you actually need it during an outage — factor the $200–$400/year maintenance cost into your long-term decision, not just the upfront installation price.
How the Calculator Works
Total Cost = Base Install (by type/size) + Propane Tank (if new) + Difficult Site Surcharge (if applicable)
The base install price reflects a complete standard installation for the selected type and size — including the unit, transfer switch, standard-length gas and electrical connections, pad, and permit for standby units, or the unit and manual transfer switch for portable setups. A new propane tank surcharge applies only when selected, since existing gas or propane service doesn't require it. The difficult site surcharge applies when the gas or electrical run is longer than standard or the site has other complicating factors.
Factors That Affect Your Actual Cost
Regional Demand and Labor Rates
Generator installation has become one of the fastest-growing residential electrical service categories, driven by extreme weather and aging grid infrastructure in states like Texas, California, Florida, and the Northeast. High-demand regions sometimes see both higher pricing and longer installer wait times, especially after major storm events.
Electrical Panel Capacity
The automatic transfer switch needs to match your panel's service amperage (100A, 200A, or larger), and installation requires a continuous-load calculation. If your panel is already outdated or undersized, addressing that may be part of this project. Try our Electrical Load Calculator for a rough estimate of where you stand, then see our Electrical Panel Upgrade Cost Calculator if panel work is also needed.
Brand and Dealer Markup
Generac dominates residential market share with a large certified-dealer network; Kohler and Cummins compete on build quality at a modest premium. Authorized dealer programs sometimes carry higher markup than independent electricians, so comparing both types of installer is worth doing.
Financing Availability
Given the size of a standby generator investment, financing through dealers or third-party lenders is commonly available and worth asking about if the full upfront cost is a barrier — this doesn't change the total cost but can make the timing more manageable.
Frequently Asked Questions
- Angi 2026 Whole House Generator Cost Guide — Installation cost averages, transfer switch pricing, permit requirements. Referenced for cost tables and safety guidance. Angi, 2026.
- HomeGuide Generator Cost Guide 2026 — Portable vs. standby comparison, fuel consumption and runtime data, generator lifespan. Referenced for the types guide and FAQ. HomeGuide, 2026.
- ProjectCostPro Whole-House Generator Cost Guide 2026 — Per-kW installed pricing, cost component breakdown, regional cost multipliers. Referenced for the sizing guide and cost breakdown table. ProjectCostPro, 2026.
- PipelineOn Generator Installation Industry Report 2026 — Contractor-side pricing data, regional demand trends, brand market share. Referenced for the factors section. PipelineOn, 2026.
Pricing reflects 2026 US national average contractor pricing. Costs vary significantly by region, home electrical load, and site conditions — always get 3 local, itemized quotes from licensed installers before committing to a generator project. ConstructlyTools does not have a paid relationship with any contractor, generator manufacturer, or supplier referenced on this page.
Prakash
Prakash is the founder and editor of ConstructlyTools. He researches, develops, and maintains construction calculators, material estimators, cost guides, and DIY planning resources designed to help homeowners, contractors, and builders make informed project decisions.
Every calculator and guide is researched using trusted industry references, published building standards, manufacturer specifications, and reliable construction pricing sources. Each page is reviewed for formula accuracy, pricing methodology, readability, and practical usefulness before publication and is updated regularly as standards or market prices change.
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