Whole House Generator Cost Calculator
A whole house generator cost calculator adds a base cost to size × rate: a 20 kW unit at $700 per kW plus $2,000 for pad and permits comes to $16,000.
Estimating whole house generator cost
A whole house generator cost calculator gives a rough installed price for a standby generator. Enter the generator size in kilowatts, an installed rate in dollars per kilowatt, and a base cost for the pieces that do not scale with size. The tool multiplies the size by the rate and adds the base.
Think of a price tag in two parts. One part grows with the size of the machine. The other part is a fixed fee you pay no matter how big it is, such as the permit and the pad it sits on.
The formula in plain words
Estimated cost = base cost + (size in kW × rate per kW).
The rate is meant to cover the generator and the work to install it. The base covers permits, the pad, and the transfer switch.
Worked example: a 20 kW unit
The size is 20 kW, the rate is $700 per kW, and the base is $2,000.
- Size cost: 20 × $700 = $14,000
- Base: $2,000
- Total: $14,000 + $2,000 = $16,000
Worked example: a 22 kW unit with different rates
The size is 22 kW, the quoted rate is $650 per kW, and the base is $3,500.
- Size cost: 22 × $650 = $14,300
- Base: $3,500
- Total: $14,300 + $3,500 = $17,800
Total cost by generator size
All rows use $700 per kW and a $2,000 base.
| Generator size | Size cost | Total |
|---|---|---|
| 10 kW | $7,000 | $9,000 |
| 14 kW | $9,800 | $11,800 |
| 20 kW | $14,000 | $16,000 |
| 24 kW | $16,800 | $18,800 |
| 38 kW | $26,600 | $28,600 |
Changing the rate by $100 per kW moves a 20 kW job by $2,000. At $600 the total is $14,000, and at $800 it is $18,000.
Choosing a size
The size drives the price, so it is worth getting right. A generator that is too small trips off when a big load starts. One that is too big costs more up front and burns more fuel to do the same job.
List what you want to run in an outage. A furnace blower, well pump, refrigerator, and a few lights is a smaller load than central air and an electric range. Motors take more power to start than to run, so account for that surge. The generator size calculator helps total it up.
What an installation includes
Beyond the generator, an installation involves a pad, a transfer switch that safely isolates the house from the grid, a fuel line from natural gas or propane, wiring, and permits. The fuel line and the electrical hookup should be done by licensed tradespeople and inspected. If the quote leaves any of these out, ask what you would pay extra.
Ongoing costs matter too. Standby units need periodic maintenance, and fuel use adds up during long outages. This calculator covers the installed price and not the running costs.
Getting useful quotes
Get at least two written quotes from licensed installers. Give each the same list of loads so the sizes are comparable. Ask what the price includes, who pulls the permit, what the warranty covers, and how service is handled. Then run each quote through the tool by entering its kW size, dividing the total by the size to find the real rate per kW, and typing the base cost the installer lists. That lets you compare quotes of different sizes on the same footing.
Common mistakes
- Treating the default rate as a market price. Always replace it with a real quote.
- Leaving out the base cost. Permits, the pad, and the transfer switch are real expenses.
- Sizing by price instead of load. Size comes first.
- Skipping the permit. Unpermitted work can create trouble with insurance and with selling the house.
- Forgetting the fuel supply. Running a new gas line can add to the bill.
- Using it for portable generators. This tool is for permanent standby systems.
Related calculators
Work out how big the machine needs to be with the generator size calculator. The transformer size calculator converts a load to kVA, and the mini split cost calculator prices a heating and cooling load you may want to back up.
Frequently asked questions
How do I estimate whole house generator cost?
Multiply the generator size in kW by an installed rate per kW, then add a base cost for the pad, permits, and transfer switch. At 20 kW, $700 per kW, and $2,000 base, the estimate is $16,000.
Are the default rates real quotes?
No. The $700 per kW and $2,000 base are placeholders. Replace them with numbers from licensed installers in your area, since prices vary by region, brand, and site.
What size generator do I need?
That depends on which loads you want to run during an outage. Add up the running and starting watts of your essentials. The generator size calculator on this site helps with that step.
What is in the base cost?
The field is meant for fixed costs that do not scale with size, such as the concrete or composite pad, the permit, and the transfer switch. Ask your installer what their quote includes.
Who should install a standby generator?
A licensed electrician, along with a licensed plumber or gas fitter for the fuel line. A standby generator ties into your electrical panel and fuel supply, so it needs permits, inspection, and correct installation.
Estimates only. Verify quantities with your supplier before purchasing.