Home Generator Installation Cost Calculator

Getting an answer takes five quick steps. The tool builds the installed total from four parts, which are the generator unit, the transfer switch, the installation labor and the permit.

1. Choose your home size. The calculator fills in a typical generator size, and you can change the kW number after.
2. Type the generator size in kW. Most homes use 14 to 26 kW.
3. Pick the fuel type. Natural gas, propane and diesel each carry a different cost per kW, and the unit cost is the size times that rate.
4. Pick the transfer switch type and the installation difficulty. An automatic switch costs more than a manual one, and a complex site costs more than a standard one.
5. Type the permit and inspection cost, then press Calculate, or press Enter. The installed total appears first and large, with the unit cost, the switch, the labor, the permit and the cost per kW below. Press Reset to clear the form and start over.

Total installed cost = (Generator size in kW × Cost per kW for the fuel type) + Transfer switch cost + Installation labor + Permit cost. Cost per kW = Total installed cost ÷ Generator size in kW.

Generator size in kW is the rated power of the unit. Cost per kW is the generator unit price for the fuel type, and it is $300 for natural gas, $330 for propane and $400 for diesel. Transfer switch cost is $2,000 for an automatic switch and $1,000 for a manual switch. Installation labor is $2,500 for a standard install and $4,000 for a complex install. Permit cost is the electrical and gas permit plus inspection, and typical permits run $200 to $600.

The formula follows the standard installed-cost breakdown, which adds the generator unit, the transfer switch, the pad and fuel work, the permit and the labor. This calculator leaves out the pad and the fuel line work, because those vary too much by site, so ask your installer what they add.

You install a 20 kW natural gas generator with an automatic transfer switch on a standard site, and the permit costs $400. Here is exactly what the calculator does.

1. Generator unit cost = 20 kW × $300 per kW = $6,000.00.
2. Add the automatic transfer switch: $6,000.00 + $2,000.00 = $8,000.00.
3. Add standard installation labor: $8,000.00 + $2,500.00 = $10,500.00.
4. Add the permit: $10,500.00 + $400.00 = $10,900.00.
5. Cost per kW = $10,900.00 ÷ 20 kW = $545.00 per kW.

As a check, a 22 kW whole-home system typically installs for $9,000 to $13,500, so this 20 kW result sits inside the published range.

Size is the biggest price driver, because every extra kW adds unit cost and usually more electrical work. The table below shows the typical installed ranges for 2026, so you can see where your own estimate lands.

Our worked example at $10,900 sits inside the 18 to 22 kW band. If your estimate lands far outside the band for your size, check the fuel type and the difficulty setting first.

Fuel is the first lever. Natural gas is cheapest to connect when your home already has a utility gas line, with a hookup of $500 to $1,500. Propane needs a dedicated tank, which runs $2,500 to $5,000 for a 500 to 1,000 gallon tank, and diesel units cost more per kW than gas units of the same size.

The transfer switch is next. An automatic switch starts the generator by itself within seconds of an outage and costs $1,800 to $5,500 installed depending on amperage and circuits, while a manual switch costs $1,000 to $2,200. This calculator uses $2,000 for automatic and $1,000 for manual.

Site work adds the rest. A long run from the meter or panel adds pipe, trenching and labor, a slope or tight access adds site preparation, and a concrete pad costs $200 to $600. Insulating first can even drop you a size tier, so check the load with our insulation calculator before you size the generator. If the install needs a pad, price it with our concrete calculator.

Sizing by square footage alone is the most common mistake. The real size comes from a load calculation, which adds up the loads that run at the same time, such as the central air conditioner, the electric range and the dryer. Undersize and the generator trips on overload during the first outage, oversize and you pay for kW you never use.

Comparing quotes that include different things is the second mistake. One quote may include the transfer switch, the pad and the permit, while another leaves them out, so the cheaper number can be the more expensive job. Ask every installer for the same list, which is the generator model and kW, the switch, the pad, the fuel work and the permit, then run each quote through this calculator to compare like with like.

Finally, remember what this estimate leaves out. It covers the unit, the switch, the labor and the permit, but not the concrete pad, the gas line or propane tank, or any panel upgrade. For wider backup power planning, our van life solar calculator shows how solar sizing works off grid, and our greenhouse heating cost calculator prices keeping a heated space warm through cold weather.

This calculator gives an estimate for planning and is for informational purposes only, not a contractor quote. Actual installation prices depend on your generator model, your fuel setup, your site, your panel and local permit fees. Get a load calculation and written bids from licensed installers before you buy. See our disclaimer.