Generator purchase costs
Whole house generator cost calculator
No result yet. Enter your values, then calculate.
Method and printable worksheet
Inputs are your assumptions unless a document is supplied. Check source numbers and compatibility in the matching manufacturer manual.
Itemized total interval = sum mutually exclusive line-item low/high endpoints plus explicitly applicable extras. Bundled mode uses published package interval plus separately documented exclusions only; never add already-included transfer switch or labor. Taxes apply only to user-defined taxable subtotal with a supplied rate; otherwise excluded/UNKNOWN. Incomplete required lines return known subtotal plus UNKNOWN items, not a complete total.
Synthetic arithmetic check: equipment $4000-$5000 and non-overlapping installation $2000-$3000 yields $6000-$8000 before excluded fees. These are example inputs, not current project cost data.
| Item / exact model | Quantity and units | Low / running | High / starting | Source and date |
|---|---|---|---|---|
| Record 1 | ________ | ________ | ________ | ________ |
| Record 2 | ________ | ________ | ________ | ________ |
| Record 3 | ________ | ________ | ________ | ________ |
Worksheet: https://bestgeneratorforhome.com/whole-house-generator-cost/whole-house-generator-cost-calculator/
Review the planning guide. Check the exact manual before using any result. Report a method correction.
The short answer
Whole house generator cost calculator: start with the editable national reference budget, or enter separate quote lines. The starting $6,000-$16,000 envelope combines HomeGuide and Generac published guidance. It is not a local quote or average. Local permits, extra fees and tax remain unknown until priced. Do not add a bundled item twice.
Last updated October 2026
What's covered7
This calculator starts with an editable national budget for an installed standby generator. It adds cost lines that do not overlap. It also marks the lines it cannot fill, so you can see what a quote still needs to cover.
The worksheet lists six core installed-system cost lines plus other fees. They are the generator, transfer equipment, electrical work, fuel work, base or site preparation, and permits. Add their low and high amounts only when each line has a source and a stated scope. If a required line is missing, the result is a partial subtotal plus a list of unknown items.
How the whole house generator cost calculator compares its national budget and quote modes
| Feature | Itemized mode | Bundled mode |
|---|---|---|
| What you enter | Low and high amounts for each line | One published or quoted package range |
| What gets added | Separate lines that do not overlap | Only costs the source says are excluded |
| Main risk | Two lines covering the same work | Adding an item the package already includes |
| Missing data | Shows known subtotal plus UNKNOWN lines | Shows the package range plus UNKNOWN exclusions |
| Tax | Applied only to a taxable subtotal you define, at a rate you enter | Same rule |
| Maintenance | Kept out of the one-time total | Kept out of the one-time total |
Scroll for more →
Start with the national reference mode, or choose your own itemized or bundled quote. The calculator does not mix quote modes. Mixing them could count the same switch or the same labor twice.
Inputs that change the installed range
Backup scope
Record your scope in the system description field. Essential-circuit backup covers a chosen group of circuits. Managed whole-house backup covers more of the panel.
Scope can affect other lines, such as transfer equipment and electrical work. The description field keeps that scope beside your model and fuel. That way you can see what changed and why.
Fuel and documented capacity
Record your fuel and exact model in that same description field. Some standby units have different ratings on each fuel. These ratings come from the makers' own documents.
| Model | Propane rating | Natural gas rating | Voltage in source |
|---|---|---|---|
| Generac Guardian 26 kW (G007290-0, G007291-0) | 26 kW max continuous | 22.5 kW max continuous | 240 V rated |
| KOHLER 20RCA | 20 kW | 18 kW | 120/240 V single-phase option |
| Cummins RS20A | 20 kW | 18 kW | 120/240 V single phase |
Scroll for more →
These ratings help you pick a model band. They do not show that a model fits your loads. Fit needs your running and starting loads, voltage and connection details. A capacity label alone cannot settle that.
The KOHLER page lists its automatic transfer switch as sold separately. So a KOHLER generator line may not include transfer equipment. Check what the exact order includes before you add lines.
Itemized line items
The national mode starts at $6,000 to $16,000. It spans two named publications, not one local installer. HomeGuide, published December 30, 2025, lists $6,000 to $11,000 for the unit and labor. Generac lists $8,000 to $16,000 for an installed system.
Its page is undated. This is a reference envelope, not an average or a local quote. Individual component prices remain blank unless you supply a quote.
Transfer equipment varies a lot. Reliance Controls lists the 306CRK as a six-circuit, 30 A manual kit. It contains a switch, an inlet and a ten-foot cord. Generac lists the HomeLink 6853 as a 30 A pre-wired manual kit.
Its sheet says upgrades depend on system requirements.
The Reliance TF152W is rated 125 V and 15 A for one circuit. Its maker lists 1875 maximum generator running watts. These kits do different jobs. A kit listing names its contents.
It does not prove the kit suits your generator or panel.
Bundled package mode
Bundled mode uses one package range. Then it adds only items the source names as excluded. If the package includes the switch and labor, do not add them again.
Generac publishes an indicative US total of $8,000 to $16,000. Generac says it covers the generator, system equipment and materials, and installation. The page shows no publication date.
This figure is manufacturer guidance. It is not an independent national median or a quote. Generac notes that location, fuel line, site and permit scope change the real total.
Do not split a bundled total into labor and parts. The checked cost source does not give an itemized quote. Any split would be a made-up number.
Site extras, permits and tax
You enter site extras yourself, and only if they apply. The tool has no national default for them.
Permit and utility rules come from your local authority and your utility. This page has not chosen an example area. So permit costs stay UNKNOWN here. We do not apply one area's rules nationwide.
Tax applies only to a subtotal you mark as taxable. You also enter the rate. Without both, tax stays excluded or UNKNOWN.
How the math works
Itemized mode adds the low ends of all lines to get the low total. It adds the high ends to get the high total. Enter separate extras on the other-fees line. Mark a line as already included only when its source confirms that scope.
Here is an illustrative example. It is arithmetic only, not current pricing. Equipment is $4,000 to $5,000. Separate installation is $2,000 to $3,000.
The planning range is $6,000 to $8,000 before excluded fees.
Bundled mode starts with the package range. It then adds only documented exclusions. If a required line has no amount, you get the known subtotal and a list of UNKNOWN lines.
What stays unknown
Floor area alone does not produce an estimate. Load depends on which circuits you back up and what runs on them.
The tool uses no national location multiplier. Reusing an old transfer switch or gas line stays UNKNOWN. That changes only when a document confirms it works with the new unit.
Fuel work has its own checks. Fuel pressure and flow, exact instructions and source voltage are separate questions. Electric watts do not tell you gas flow.
Placement also matters. Standby clearances come from the unit's own manual and local rules. Wiring and gas work belong to licensed trades.
Maintenance is a repeat cost. The tool keeps it out of the one-time installed total.
Sources, method and limits
The budget defaults combine a national cost publisher with manufacturer installed-system guidance. Model records retain their source link, exact model, units and scope.
It also notes whether a value was observed, derived or assumed.
When two documents disagree, we use the more detailed primary document. For example, we use the Cummins brochure ratings. Amounts with no source stay blank.
This page has limits. Its two budget references have different scopes and dates. Their combined envelope is not a statistical average. It has no local permit data.
It does not compare full transfer system requirements.
The interactive calculation needs JavaScript. Without it, the page still shows the formulas, the source tables and a blank worksheet. The printout lists your inputs, the method, the range, exclusions, sources and check dates.
For wider pricing context, see the whole house generator cost guide. For one brand's published scope, see Generac generator cost.
Whole house generator cost calculator FAQs
Does this calculator give an exact quote?
No. It builds a planning range from sourced line items or a published package range. A real price depends on your site, panel, fuel work, permits and the exact equipment order. The tool shows which of those lines are still unknown, so you can see what a quote must cover.
Is Generac's $8,000 to $16,000 figure a national average?
No. Generac calls it an indicative US total for a complete install. It includes the generator, system equipment and materials, and installation. It is one maker's guidance, not an independent survey.
The page shows no publication date.
Can I size a generator from square footage here?
No. Floor area does not tell you electrical load. Load depends on which circuits you back up and what equipment runs on them. Use a documented model band for budgeting only.
Then confirm the fit with running and starting loads, voltage and the exact model's documents.
Why is maintenance left out of the total?
Maintenance is a repeat cost, not part of the one-time install. Mixing the two would make the capital budget harder to compare. The tool lists maintenance as excluded, so it stays visible. You can then plan it as a separate yearly budget line using your model's own documents.
Whole house generator cost calculator verdict
Whole house generator cost calculator: Use itemized mode when you have separate amounts for each line and know that none overlap. Use bundled mode when you have one package range and a clear list of its exclusions. Generac's published range is one reference point, not a quote.
In both modes, permits, site extras, fuel work and equipment reuse stay unknown until documents for your site fill them in.
Continue your backup plan
Choose your next step
For the wider cost picture, read the whole house generator cost guide, then follow its link to the home generator picks. Match the exact fuel, voltage and starting limits to your result before you choose.